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Maclaurin Series

Practice exam-style IB Math AA questions for Maclaurin Series, aligned with the syllabus and grouped by topic.

Verified by Karim
Verified by Karim
Paper
Difficulty
Status
Level
Question 1
HL • Paper 1
Easy
Non Calculator
HL • Paper 1
Easy
Non Calculator

The function ff is defined by f(x)=e2xf(x)=e^{-2x}.

A

Find the Maclaurin series for f(x)f(x) up to and including the term in x3x^3.

[2]
B

Hence find a polynomial approximation to e15e^{-\frac{1}{5}}, giving your answer as a single fraction.

[2]
Question 2
HL • Paper 2
Easy
Calculator Permitted
HL • Paper 2
Easy
Calculator Permitted

Consider the function g(x)=1+3xg(x)=\sqrt{1+3x}.

A

Find the Maclaurin series for g(x)g(x) up to and including the term in x3x^3.

[3]
B

Hence find limx01+3x132xx2\displaystyle \lim_{x\to 0}\frac{\sqrt{1+3x}-1-\frac{3}{2}x}{x^2}.

[2]
Question 3
HL • Paper 1
Medium
Non Calculator
HL • Paper 1
Medium
Non Calculator

Consider the function f(x)=13xf(x)=\sqrt{1-3x}.

A

Find the Maclaurin series for f(x)f(x) up to and including the term in x3x^3.

[4]
B

State the interval of convergence for this series.

[1]
Question 4
HL • Paper 1
Medium
Non Calculator
HL • Paper 1
Medium
Non Calculator

Let f(x)=exsin(2x)f(x)=e^x\sin(2x).

A

Find the Maclaurin series for f(x)f(x) up to and including the term in x4x^4.

[5]
Question 5
HL • Paper 1
Medium
Non Calculator
HL • Paper 1
Medium
Non Calculator

Consider the function f(x)=arctan(3x2)f(x)=\arctan(3x^2).

A

Determine the Maclaurin series for f(x)f(x) up to and including the term in x6x^6.

[3]
B

State the set of values of xx for which this series converges.

[1]
Question 6
HL • Paper 1
Medium
Non Calculator
HL • Paper 1
Medium
Non Calculator

Let

I(x)=0xln(1+t)tdtI(x)=\int_0^x \frac{\ln(1+t)}{t}\,\mathrm{d}t
A

Using the Maclaurin series for ln(1+t)\ln(1+t), find the Maclaurin series for ln(1+t)t\dfrac{\ln(1+t)}{t} up to and including the term in t3t^3.

[2]
B

Hence find the Maclaurin series for I(x)I(x) up to and including the term in x4x^4.

[3]
Question 7
HL • Paper 1
Medium
Non Calculator
HL • Paper 1
Medium
Non Calculator

The geometric series is

11+x=1x+x2x3+x4\frac{1}{1+x}=1-x+x^2-x^3+x^4-\cdots
A

By differentiating term by term, find the Maclaurin series for 1(1+x)2\dfrac{1}{(1+x)^2} up to and including the term in x4x^4.

[4]
B

State the interval of convergence of this series.

[1]
Question 8
HL • Paper 1
Medium
Non Calculator
HL • Paper 1
Medium
Non Calculator

A

Find

limx0ln(1+2x)sin(2x)x2\lim_{x\to 0}\frac{\ln(1+2x)-\sin(2x)}{x^2}
[4]
Question 9
HL • Paper 2
Medium
Calculator Permitted
HL • Paper 2
Medium
Calculator Permitted

Let f(x)=e2xln(1+x)f(x)=e^{2x}\ln(1+x).

A

Find the Maclaurin series for f(x)f(x) up to and including the term in x4x^4.

[4]
B

Use your series to estimate 00.2e2xln(1+x)dx\displaystyle \int_0^{0.2} e^{2x}\ln(1+x)\,\mathrm{d}x.

[2]
Question 10
HL • Paper 2
Medium
Calculator Permitted
HL • Paper 2
Medium
Calculator Permitted

Let h(x)=arctanx1+x2h(x)=\dfrac{\arctan x}{1+x^2}.

A

Find the Maclaurin series for h(x)h(x) up to and including the term in x5x^5.

[4]
B

Use your series to estimate h(0.4)h(0.4).

[2]
Question 11
HL • Paper 2
Medium
Calculator Permitted
HL • Paper 2
Medium
Calculator Permitted

Let

I(x)=0x1cos(t2)t2dtI(x)=\int_0^x \frac{1-\cos(t^2)}{t^2}\,\mathrm{d}t

where the integrand is defined by its limiting value at t=0t=0.

A

Find the Maclaurin series for I(x)I(x) up to and including the term in x11x^{11}.

[4]
B

Use your series to estimate I(1)I(1).

[1]
Question 12
HL • Paper 2
Medium
Calculator Permitted
HL • Paper 2
Medium
Calculator Permitted

Let

f(x)=1ex+cosxf(x)=\frac{1}{e^x+\cos x}
A

Determine the Maclaurin series for f(x)f(x) up to and including the term in x3x^3.

[4]
B

Hence find f(0)f'''(0).

[1]
Question 13
HL • Paper 1
Medium
Non Calculator
HL • Paper 1
Medium
Non Calculator

A function yy satisfies the differential equation

y=y+xy'=y+x

with y(0)=2y(0)=2.

A

Find y(0)y'(0), y(0)y''(0), y(0)y'''(0) and y(4)(0)y^{(4)}(0).

[3]
B

Hence find the Maclaurin series for yy up to and including the term in x4x^4.

[2]
Question 14
HL • Paper 1
Medium
Non Calculator
HL • Paper 1
Medium
Non Calculator

Let

h(x)=ex(1+ax)12h(x)=e^x(1+ax)^{-\frac{1}{2}}

where aa is a real constant. The coefficient of x2x^2 in the Maclaurin series for h(x)h(x) is 11.

A

Find the possible values of aa.

[6]
Question 15
HL • Paper 1
Medium
Non Calculator
HL • Paper 1
Medium
Non Calculator

Let f(x)=excosxf(x)=e^x\cos x.

A

Find the Maclaurin series for f(x)f(x) up to and including the term in x4x^4.

[5]
Question 16
HL • Paper 1
Medium
Non Calculator
HL • Paper 1
Medium
Non Calculator

Let

f(x)=ln(1+x)1xf(x)=\frac{\ln(1+x)}{1-x}
A

Find the Maclaurin series for f(x)f(x) up to and including the term in x3x^3.

[4]
B

Hence find

limx0f(x)xx22x3\lim_{x\to 0}\frac{f(x)-x-\dfrac{x^2}{2}}{x^3}
[2]
Question 17
HL • Paper 2
Medium
Calculator Permitted
HL • Paper 2
Medium
Calculator Permitted

The Maclaurin series for tanx\tan x may be found using the series for sinx\sin x and cosx\cos x.

A

Show that tanx=x+x33+2x515+\tan x=x+\dfrac{x^3}{3}+\dfrac{2x^5}{15}+\cdots.

[4]
B

Using this series, estimate the smallest positive value of xx for which tan(2x)2x=0.100\tan(2x)-2x=0.100.

[2]
Question 18
HL • Paper 2
Medium
Calculator Permitted
HL • Paper 2
Medium
Calculator Permitted

A function yy satisfies the differential equation

y+xy+y=0y''+xy'+y=0

with y(0)=1y(0)=1 and y(0)=0y'(0)=0.

A

Find y(0)y''(0) and y(0)y'''(0).

[2]
B

Find the Maclaurin series for yy up to and including the term in x6x^6.

[4]
Question 19
HL • Paper 2
Medium
Calculator Permitted
HL • Paper 2
Medium
Calculator Permitted

Let L(x)=ln(cosx)L(x)=\ln(\cos x).

A

Find the Maclaurin series for L(x)L(x) up to and including the term in x6x^6.

[4]
B

Hence find limx0ln(cosx)+x22+x412x6\displaystyle \lim_{x\to 0}\frac{\ln(\cos x)+\frac{x^2}{2}+\frac{x^4}{12}}{x^6}.

[2]
Question 20
HL • Paper 2
Medium
Calculator Permitted
HL • Paper 2
Medium
Calculator Permitted

Let p(x)=arctan(ex1)p(x)=\arctan(e^x-1).

A

Find the Maclaurin series for p(x)p(x) up to and including the term in x4x^4.

[4]
B

Using this series, estimate the smaller positive solution (the solution close to x=0x=0) of arctan(ex1)=0.500\arctan(e^x-1)=0.500.

[2]
Question 21
HL • Paper 2
Medium
Calculator Permitted
HL • Paper 2
Medium
Calculator Permitted

Consider the third-degree Maclaurin polynomial for ln(12x)\ln(1-2x).

A

Write down this polynomial and state the interval of convergence of the corresponding infinite series.

[3]
B

Use a GDC to determine the largest positive value of xx for which ln(12x)P3(x)=0.005|\ln(1-2x)-P_3(x)|=0.005.

[2]
Question 22
HL • Paper 1
Medium
Non Calculator
HL • Paper 1
Medium
Non Calculator

Let f(x)=(1+x)12ln(1+2x)f(x)=(1+x)^{-\frac12}\ln(1+2x), where xx is close to 00.

A
I.

Find the Maclaurin series for (1+x)12(1+x)^{-\frac12} up to and including the term in x3x^3.

[2]
II.

Find the Maclaurin series for ln(1+2x) \ln(1+2x) up to and including the term in x3x^3.

[2]
B

Hence find the Maclaurin series for f(x)f(x) up to and including the term in x3x^3.

[3]
C

Hence determine limx0f(x)2x+3x2x3\lim_{x\to 0}\frac{f(x)-2x+3x^2}{x^3}

[2]
Question 23
HL • Paper 1
Medium
Non Calculator
HL • Paper 1
Medium
Non Calculator

The function GG is defined by G(x)=0xarctanttdtG(x)=\int_0^x \frac{\arctan t}{t}\,\mathrm{d}t where the integrand is defined by its limiting value at t=0t=0.

A
I.

Starting from 11+t2\dfrac{1}{1+t^2}, obtain the Maclaurin series for arctant\arctan t up to and including the term in t7t^7.

[3]
II.

State the interval of convergence of the series for arctant\arctan t.

[1]
B

Hence find the Maclaurin series for G(x)G(x) up to and including the term in x7x^7.

[3]
C

Using the first four non-zero terms of this series, find an approximate value for G(1)G(1) as a single fraction.

[2]
Question 24
HL • Paper 1
Medium
Non Calculator
HL • Paper 1
Medium
Non Calculator

For x0x\ne0, let f(x)=sinxxf(x)=\dfrac{\sin x}{x}, and define f(0)=1f(0)=1.

A
I.

Find the Maclaurin series for f(x)f(x) up to and including the term in x6x^6.

[2]
II.

Hence find the Maclaurin series for 1f(x)\dfrac{1}{f(x)} up to and including the term in x4x^4. If you did not obtain the series in part (a)(i), use f(x)=1x26+x4120+f(x)=1-\dfrac{x^2}{6}+\dfrac{x^4}{120}+\cdots.

[3]
B

Hence determine limx0xsinx1x26x4\lim_{x\to0}\frac{\dfrac{x}{\sin x}-1-\dfrac{x^2}{6}}{x^4}

[3]
Question 25
HL • Paper 1
Medium
Non Calculator
HL • Paper 1
Medium
Non Calculator

The function FF is defined by F(x)=0x(1+t2)32dtF(x)=\int_0^x (1+t^2)^{-\frac32}\,\mathrm{d}t

A
I.

Find the Maclaurin series for (1+t2)32(1+t^2)^{-\frac32} up to and including the term in t6t^6.

[3]
II.

Hence find the Maclaurin series for F(x)F(x) up to and including the term in x7x^7.

[2]
B
I.

Show that F(x)=x1+x2F(x)=\dfrac{x}{\sqrt{1+x^2}}.

[2]
II.

Hence determine limx0F(x)x+x323x58x7\lim_{x\to0}\frac{F(x)-x+\frac{x^3}{2}-\frac{3x^5}{8}}{x^7}

[2]
Question 26
HL • Paper 1
Medium
Non Calculator
HL • Paper 1
Medium
Non Calculator

Let f(x)=ex2cosxf(x)=e^{x^2}\cos x

A
I.

Write down the Maclaurin series for ex2e^{x^2} and for cosx\cos x up to and including the term in x6x^6.

[2]
II.

Hence find the Maclaurin series for f(x)f(x) up to and including the term in x6x^6.

[2]
B

Using the series from part (a), approximate 01f(x)1x2dx\int_0^1 \frac{f(x)-1}{x^2}\,\mathrm{d}x

[3]
C

Justify why every odd derivative of ff at 00 is zero.

[2]
Question 27
HL • Paper 1
Medium
Non Calculator
HL • Paper 1
Medium
Non Calculator

A function yy satisfies

y+y=xy''+y=x

with y(0)=1y(0)=1 and y(0)=0y'(0)=0.

A

By writing y=a0+a1x+a2x2+a3x3+a4x4+a5x5+y=a_0+a_1x+a_2x^2+a_3x^3+a_4x^4+a_5x^5+\cdots, determine the Maclaurin series for yy up to and including the term in x5x^5.

[6]
Question 28
HL • Paper 2
Medium
Calculator Permitted
HL • Paper 2
Medium
Calculator Permitted

The polynomial P5(x)P_5(x) is the Maclaurin polynomial for sinx\sin x up to and including the term in x5x^5.

Graphs of y=sin x and y=P5(x) on a symmetric interval.
A
I.

Write down P5(x)P_5(x).

[1]
II.

State why the error function E(x)=sinxP5(x)E(x)=\sin x-P_5(x) is an odd function.

[2]
B

Use a GDC to determine the largest positive value of xx for which

sinxP5(x)=0.001|\sin x-P_5(x)|=0.001
[2]
C

Hence state the interval, symmetric about zero, on which P5(x)P_5(x) approximates sinx\sin x with absolute error less than 0.0010.001.

[2]
D

Explain why the Maclaurin series for sinx\sin x itself converges for all real xx, but the polynomial P5(x)P_5(x) does not give a uniformly accurate approximation for all real xx.

[2]
Question 29
HL • Paper 2
Medium
Calculator Permitted
HL • Paper 2
Medium
Calculator Permitted

A function yy satisfies

y=x+y2y'=x+y^2

with y(0)=1y(0)=1.

A

Determine the Maclaurin series for yy up to and including the term in x4x^4.

[5]
B

Use this series to estimate y(0.2)y(0.2).

[1]
Question 30
HL • Paper 2
Medium
Calculator Permitted
HL • Paper 2
Medium
Calculator Permitted

For x0x\ne 0, define F(x)=(1+x)1/xF(x)=(1+x)^{1/x}, and define F(0)=eF(0)=e by its removable continuous extension. Show that the Maclaurin series for F(x)F(x), up to and including the term in x3x^3, is e(1x2+11x2247x316+)e\left(1-\dfrac{x}{2}+\dfrac{11x^2}{24}-\dfrac{7x^3}{16}+\cdots\right).

A

Show that the Maclaurin series for F(x)F(x), up to and including the term in x3x^3, is e(1x2+11x2247x316+)e\left(1-\dfrac{x}{2}+\dfrac{11x^2}{24}-\dfrac{7x^3}{16}+\cdots\right).

[5]
B

Hence find limx0(1+x)1/xex\displaystyle \lim_{x\to 0}\frac{(1+x)^{1/x}-e}{x}.

[1]
Question 31
HL • Paper 3
Medium
Calculator Permitted
HL • Paper 3
Medium
Calculator Permitted

The value of π\pi can be approximated using π=6arcsin(12)\pi=6\arcsin\left(\frac12\right). In this question, a Maclaurin series for arcsinx\arcsin x is obtained by integration.

A
I.

Use the binomial expansion to show that 11t2=1+t22+3t48+5t616+\frac{1}{\sqrt{1-t^2}}=1+\frac{t^2}{2}+\frac{3t^4}{8}+\frac{5t^6}{16}+\cdots

[3]
II.

Hence find the Maclaurin series for arcsinx\arcsin x up to and including the term in x7x^7.

[2]
B

Use the series from part (a) to estimate π\pi.

[1]
C

The next term in the series for arcsinx\arcsin x is 35x91152\frac{35x^9}{1152}. You may use that, for the terms of this series evaluated at x=12x=\frac12, the ratio of each term to the preceding term is less than 14\frac14. Use this to find an upper bound for the error in your estimate in part (b), and state whether the estimate is an underestimate or an overestimate.

[2]
Question 32
HL • Paper 1
Hard
Non Calculator
HL • Paper 1
Hard
Non Calculator

A function yy satisfies the differential equation y+2xy+2y=0y''+2xy'+2y=0 with y(0)=1y(0)=1 and y(0)=0y'(0)=0.

A
I.

Find y(0)y''(0) and y(0)y'''(0).

[3]
II.

Find y(4)(0)y^{(4)}(0) and y(5)(0)y^{(5)}(0). If you did not obtain y(0)=2y''(0)=-2 and y(0)=0y'''(0)=0, use these values in this part.

[3]
B

Hence find the Maclaurin series for yy up to and including the term in x5x^5.

[3]
C

Using this series, approximate 01ydx\displaystyle\int_0^1 y\,\mathrm{d}x.

[2]
Question 33
HL • Paper 1
Hard
Non Calculator
HL • Paper 1
Hard
Non Calculator

For a real constant aa, define fa(x)=eaxcosxf_a(x)=e^{ax}\cos x

A
I.

Find the Maclaurin series for fa(x)f_a(x) up to and including the term in x4x^4.

[4]
II.

Given that the coefficient of x3x^3 is zero and a>0a>0, find aa.

[2]
B

Hence determine limx0e3xcosx13xx2x4\lim_{x\to0}\frac{e^{\sqrt3 x}\cos x-1-\sqrt3 x-x^2}{x^4}

[3]
Question 34
HL • Paper 1
Hard
Non Calculator
HL • Paper 1
Hard
Non Calculator

A function yy satisfies the differential equation y=xyy''=xy with y(0)=0y(0)=0 and y(0)=1y'(0)=1. Suppose y=a0+a1x+a2x2+a3x3+y=a_0+a_1x+a_2x^2+a_3x^3+\cdots

A
I.

Write down a0a_0, a1a_1 and a2a_2.

[2]
II.

By substituting the series into the differential equation, show that (n+2)(n+1)an+2=an1for n1(n+2)(n+1)a_{n+2}=a_{n-1}\quad \text{for } n\ge1

[2]
B

Hence find the Maclaurin series for yy up to and including the term in x7x^7.

[3]
C

Using this series, find an approximate value for y(1)y(1) as a single fraction.

[2]
Question 35
HL • Paper 1
Hard
Non Calculator
HL • Paper 1
Hard
Non Calculator

Let

f(x)=ln(1+sinx)f(x)=\ln(1+ \sin x)
A
I.

Write down the Maclaurin series for sinx\sin x up to and including the term in x5x^5.

[1]
II.

Using the Maclaurin series for ln(1+u)\ln(1+u), find the Maclaurin series for f(x)f(x) up to and including the term in x5x^5.

[5]
B

Hence determine limx0ln(1+sinx)x+x22x36+x412x5\lim_{x\to0}\frac{\ln(1+\sin x)-x+\frac{x^2}{2}-\frac{x^3}{6}+\frac{x^4}{12}}{x^5}

[2]
Question 36
HL • Paper 1
Hard
Non Calculator
HL • Paper 1
Hard
Non Calculator

Let h(x)=arctan(sinx)h(x)=\arctan(\sin x)

A
I.

Write down the Maclaurin series for arctanu\arctan u up to and including the term in u5u^5.

[1]
II.

Find the Maclaurin series for h(x)h(x) up to and including the term in x5x^5.

[4]
B
I.

Hence find h(0)h'(0), h(0)h'''(0) and h(5)(0)h^{(5)}(0).

[3]
II.

Determine limx0h(x)x+x32x5\lim_{x\to0}\frac{h(x)-x+\frac{x^3}{2}}{x^5}

[2]
Question 37
HL • Paper 1
Hard
Non Calculator
HL • Paper 1
Hard
Non Calculator

A function yy satisfies y=(1+x)y+x2y'=(1+x)y+x^2 with y(0)=1y(0)=1.

A
I.

Find y(0)y'(0), y(0)y''(0), y(0)y'''(0) and y(4)(0)y^{(4)}(0).

[5]
II.

Hence find the Maclaurin series for yy up to and including the term in x4x^4. If you did not obtain the derivative values in part (a)(i), use y(0)=1y'(0)=1, y(0)=2y''(0)=2, y(0)=6y'''(0)=6 and y(4)(0)=12y^{(4)}(0)=12.

[2]
B

Using this series, approximate 01ydx\displaystyle\int_0^1 y\,\mathrm{d}x.

[2]
Question 38
HL • Paper 1
Hard
Non Calculator
HL • Paper 1
Hard
Non Calculator

Let L(x)=ln(1+x1x),1<x<1L(x)=\ln\left(\frac{1+x}{1-x}\right),\qquad -1<x<1

A
I.

Using the Maclaurin series for ln(1+x)\ln(1+x) and ln(1x)\ln(1-x), find the Maclaurin series for L(x)L(x) up to and including the term in x5x^5.

[3]
II.

State the interval of convergence of the series for L(x)L(x).

[1]
B

Let M(x)=1x2L(x)M(x)=\sqrt{1-x^2}\,L(x). Find the Maclaurin series for M(x)M(x) up to and including the term in x5x^5.

[4]
C

Hence determine limx0M(x)2x+x33x5\lim_{x\to0}\frac{M(x)-2x+\frac{x^3}{3}}{x^5}

[2]
Question 39
HL • Paper 2
Hard
Calculator Permitted
HL • Paper 2
Hard
Calculator Permitted

The function ff is defined by

f(x)=ex2cos(3x),xRf(x)=e^{-x^2}\\cos(3x), \quad x\in\mathbb{R}

The polynomial P6(x)P_6(x) is the Maclaurin polynomial for ff up to and including the term in x6x^6.

A
I.

Write down the Maclaurin series for ex2e^{-x^2} and for cos(3x)\cos(3x) up to and including terms in x6x^6.

[2]
II.

Hence determine P6(x)P_6(x).

[3]
B

Use P6(x)P_6(x) to find a polynomial approximation for

I(a)=0aex2cos(3x)dxI(a)=\int_0^a e^{-x^2}\cos(3x)\,\mathrm{d}x
[2]
C

Using the approximation from part (b), determine the two positive values of aa for which I(a)=0.240I(a)=0.240.

[3]
Question 40
HL • Paper 2
Hard
Calculator Permitted
HL • Paper 2
Hard
Calculator Permitted

Let

g(x)=ln(1+sinx)g(x)=\ln(1+\sin x)
A
I.

Write down the Maclaurin series for sinx\sin x up to and including the term in x5x^5.

[1]
II.

Hence find the Maclaurin series for g(x)g(x) up to and including the term in x5x^5.

[4]
B

Using your series, estimate the smallest positive solution of ln(1+sinx)=0.250\ln(1+\sin x)=0.250.

[2]
C

Hence determine the exact value of

limx0g(x)x+x22x36+x412x5\lim_{x\to 0}\frac{g(x)-x+\dfrac{x^2}{2}-\dfrac{x^3}{6}+\dfrac{x^4}{12}}{x^5}
[3]
Question 41
HL • Paper 2
Hard
Calculator Permitted
HL • Paper 2
Hard
Calculator Permitted

A function yy satisfies the differential equation

y+xy+2y=0y''+xy'+2y=0

with y(0)=1y(0)=1 and y(0)=0y'(0)=0.

A
I.

Find y(0)y''(0) and y(0)y'''(0).

[2]
II.

By writing y=a0+a1x+a2x2+y=a_0+a_1x+a_2x^2+ \cdots, find a recurrence relation for the coefficients.

[3]
B

Hence determine the Maclaurin series for yy up to and including the term in x6x^6.

[3]
C

Using the polynomial found in part (b), estimate the first positive value of xx for which y=0y=0.

[2]
Question 42
HL • Paper 2
Hard
Calculator Permitted
HL • Paper 2
Hard
Calculator Permitted

Consider

F(x)=11+x+x2F(x)=\frac{1}{1+x+x^2}

and

J(x)=0xF(t)dtJ(x)=\int_0^x F(t)\,\mathrm{d}t
A
I.

By writing F(x)=a0+a1x+a2x2+F(x)=a_0+a_1x+a_2x^2+ \cdots, find a recurrence relation for the coefficients.

[3]
II.

Hence write the Maclaurin series for F(x)F(x) up to and including the term in x6x^6.

[2]
B

Use the series in part (a) to find the Maclaurin series for J(x)J(x) up to and including the term in x7x^7.

[2]
C

Show that

J(x)=23(arctan(2x+13)π6)J(x)=\frac{2}{\sqrt{3}}\left(\arctan\left(\frac{2x+1}{\sqrt{3}}\right)-\frac{\pi}{6}\right)
[2]
D

Determine, using a GDC, the positive solution of J(x)=0.500J(x)=0.500. Then find the value given by solving the polynomial approximation from part (b).

[2]
Question 43
HL • Paper 2
Hard
Calculator Permitted
HL • Paper 2
Hard
Calculator Permitted

The inverse sine function may be written as

arcsinx=0x11t2dt,x<1\arcsin x=\int_0^x \frac{1}{\sqrt{1-t^2}}\,\mathrm{d}t, \quad |x|<1
A
I.

Use the binomial expansion to find the Maclaurin series for (1x2)12(1-x^2)^{-\frac12} up to and including the term in x6x^6.

[3]
II.

Hence find the Maclaurin series for arcsinx\arcsin x up to and including the term in x7x^7.

[2]
B

Use the series in part (a) with x=12x=\dfrac12 to obtain an approximation for π\pi.

[2]
C

Calculate the absolute error in the approximation from part (b).

[1]
D

Using a GDC and the series generated by integrating the binomial expansion, determine the least odd power x2n+1x^{2n+1} that must be included so that the resulting approximation to π\pi has absolute error less than 10610^{-6}.

[2]
Question 44
HL • Paper 2
Hard
Calculator Permitted
HL • Paper 2
Hard
Calculator Permitted

Let

H(x)=ex2ln(1+2x)H(x)=e^{x^2}\ln(1+2x)
A
I.

Write down the Maclaurin series for ex2e^{x^2} and ln(1+2x)\ln(1+2x) up to the terms needed to find H(x)H(x) as far as x5x^5.

[2]
II.

Hence determine the Maclaurin series for H(x)H(x) up to and including the term in x5x^5.

[3]
B

Use your series to estimate

00.25ex2ln(1+2x)dx\int_0^{0.25} e^{x^2}\ln(1+2x)\,\mathrm{d}x
[2]
C

Use a GDC to evaluate the integral in part (b) directly and hence find the absolute error in the estimate.

[2]
Question 45
HL • Paper 2
Hard
Calculator Permitted
HL • Paper 2
Hard
Calculator Permitted

A function yy satisfies

y=1+xyy'=1+xy

with y(0)=1y(0)=1.

A
I.

Let y=a0+a1x+a2x2+y=a_0+a_1x+a_2x^2+ \cdots. Find a recurrence relation for the coefficients.

[3]
II.

Hence find the Maclaurin series for yy up to and including the term in x6x^6.

[2]
B

Using the polynomial found in part (a), estimate the positive value of xx for which y=2y=2.

[2]
C

The exact solution may be written in the form

y=ex2/2(1+0xet2/2dt)y=e^{x^2/2}\left(1+\int_0^x e^{-t^2/2}\,\mathrm{d}t\right)

Verify this expression and use a GDC to find the positive value of xx for which the exact solution has value 22.

[3]
Question 46
HL • Paper 3
Hard
Calculator Permitted
HL • Paper 3
Hard
Calculator Permitted

A damped oscillation is modelled by f(x)=excos(2x)f(x)=e^{-x}\cos(2x) for 0x0.50\le x\le 0.5. A fourth-degree Maclaurin polynomial P4(x)P_4(x) is to be used as a simple approximation to f(x)f(x) near x=0x=0.

Overlay of f(x)=e^{-x}cos(2x) and P4(x) on 0≤x≤0.5.
A
I.

Write down the Maclaurin series for exe^{-x} and cos(2x)\cos(2x) up to and including the term in x4x^4.

[2]
II.

Hence find P4(x)P_4(x) for f(x)f(x).

[3]
B
I.

Use P4P_4 to estimate f(0.30)f(0.30).

[2]
II.

Using a GDC, determine the largest value of kk in 0k0.50\le k\le 0.5 such that f(x)P4(x)0.005|f(x)-P_4(x)|\le 0.005 for all 0xk0\le x\le k. If you did not obtain P4(x)P_4(x), use P4(x)=1x3x22+11x367x424P_4(x)=1-x-\frac{3x^2}{2}+\frac{11x^3}{6}-\frac{7x^4}{24}.

[3]
Question 47
HL • Paper 3
Hard
Calculator Permitted
HL • Paper 3
Hard
Calculator Permitted

For 0x0.50\le x\le 0.5, define A(x)=2arctanxarctan(2x)A(x)=2\arctan x-\arctan(2x). This function represents the small difference between two angle measurements.

Graph of A(x)=2 arctan x - arctan(2x) on 0 ≤ x ≤ 0.5.
A
I.

Write down the first four non-zero terms of the Maclaurin series for \rctanx\rctan x and for \rctan(2x)\rctan(2x).

[2]
II.

Hence find the first three non-zero terms in the Maclaurin series for A(x)A(x).

[3]
B

Use the series from part (a) to estimate A(0.4)A(0.4).

[1]
C

Justify that A(x)>0A(x)>0 for 0<x<0.50<x<0.5.

[2]
Question 48
HL • Paper 3
Hard
Calculator Permitted
HL • Paper 3
Hard
Calculator Permitted

A function yy is defined by the differential equation y=1+xyy'=1+xy with y(0)=0y(0)=0.

A
I.

By writing y=n=0anxny=\sum_{n=0}^{\infty}a_nx^n, find a recurrence relation for the coefficients.

[3]
II.

Find the Maclaurin series for yy up to and including the term in x7x^7.

[2]
B

Use your series to estimate y(0.6)y(0.6).

[1]
C

Deduce a general expression for the non-zero coefficients of the series.

[2]
Question 49
HL • Paper 3
Hard
Calculator Permitted
HL • Paper 3
Hard
Calculator Permitted

The curve y=secxy=\sec x is to be approximated near x=0x=0 by an even polynomial S6(x)=1+ax2+bx4+cx6S_6(x)=1+ax^2+bx^4+cx^6.

Expression

Role

y=secxy=\sec x

Curve near x=0x=0

S6(x)=1+ax2+bx4+cx6S_6(x)=1+ax^2+bx^4+cx^6

Even polynomial approximation

A
I.

Use the identity cosxsecx=1\cos x\sec x=1 to find aa, bb and cc.

[4]
B

Use S6S_6 to estimate 00.4secxdx\int_0^{0.4}\sec x\,\mathrm{d}x.

[2]
C

Given that the next non-zero term in the Maclaurin series for secx\sec x is positive, state whether your estimate in part (b) is an underestimate or an overestimate. Justify your answer by considering the sign of the entire omitted tail, not only the next term.

[2]
Question 50
HL • Paper 3
Hard
Calculator Permitted
HL • Paper 3
Hard
Calculator Permitted

For a real parameter aa, let Ha(x)=eaxln(1+2x)H_a(x)=e^{ax}\ln(1+2x) A value of aa is chosen so that the quadratic term in the Maclaurin series of HaH_a is zero.

A
I.

Find the coefficient of x2x^2 in the Maclaurin series for Ha(x)H_a(x).

[3]
II.

Determine the required value of aa, and find the Maclaurin series for Ha(x)H_a(x) up to and including the term in x4x^4.

[2]
B

Hence find limx0exln(1+2x)2xx3\lim_{x\to0}\frac{e^x\ln(1+2x)-2x}{x^3}

[1]
C

Using the polynomial found in part (a), estimate the small positive solution (the solution closest to x=0x=0) of exln(1+2x)=0.25e^x\ln(1+2x)=0.25. If you did not obtain a polynomial, use 2x+5x332x42x+\frac{5x^3}{3}-2x^4.

[2]
Question 51
HL • Paper 3
Hard
Calculator Permitted
HL • Paper 3
Hard
Calculator Permitted

For small positive xx, the difference D(x)=sinxarctanxD(x)=\sin x-\arctan x may be approximated by a polynomial.

Exact D(x) and quintic Maclaurin approximation for small positive x.
A
I.

Find the Maclaurin series for D(x)D(x) up to and including the term in x5x^5.

[3]
B

Find the value of aa for which limx0sinxarctanxax3x5\lim_{x\to0}\frac{\sin x-\arctan x-ax^3}{x^5} is finite and non-zero, and find the value of the limit.

[3]
C

Using the polynomial from part (a), estimate the smallest positive solution of sinxarctanx=0.020\sin x-\arctan x=0.020.

[2]
Question 52
HL • Paper 2
Hard
Calculator Permitted
HL • Paper 2
Hard
Calculator Permitted

For nZ+n\in\mathbb{Z}^{+}, define

Sn=4r=0n(1)r((1/2)2r+12r+1+(1/3)2r+12r+1)S_n=4\sum_{r=0}^{n}(-1)^r\left(\frac{(1/2)^{2r+1}}{2r+1}+\frac{(1/3)^{2r+1}}{2r+1}\right)
A
I.

Show that arctan12+arctan13=π4\arctan\dfrac{1}{2}+\arctan\dfrac{1}{3}=\dfrac{\pi}{4}.

[2]
II.

Explain why SnS_n is an approximation to π\pi.

[2]
B

Calculate S2S_2 and the absolute error S2π|S_2-\pi|.

[3]
C

Using the alternating series error estimate, show that

Snπ42n+3(122n+3+132n+3)|S_n-\pi|\le \frac{4}{2n+3}\left(\frac{1}{2^{2n+3}}+\frac{1}{3^{2n+3}}\right)
[2]
D

Determine the least value of nn for which this error bound is less than 10610^{-6}.

[2]
Question 53
HL • Paper 2
Hard
Calculator Permitted
HL • Paper 2
Hard
Calculator Permitted

For sufficiently small xx, let ww be defined implicitly by

wew=xw e^w=x

Assume that

w=a1x+a2x2+a3x3+a4x4+w=a_1x+a_2x^2+a_3x^3+a_4x^4+\cdots
A
I.

Write the Maclaurin series for ewe^w up to and including the term in w4w^4.

[1]
II.

By substituting the assumed series into wew=xwe^w=x, show that

w=xx2+3x328x43+w=x-x^2+\frac{3x^3}{2}-\frac{8x^4}{3}+\cdots
[5]
B

Use this series to estimate the solution of wew=0.300we^w=0.300.

[2]
C

Use a GDC to find the actual solution of wew=0.300we^w=0.300 and hence find the percentage error in the estimate from part (b).

[2]
Question 54
HL • Paper 2
Hard
Calculator Permitted
HL • Paper 2
Hard
Calculator Permitted

A rational approximation to exe^x is given by

R(x)=1+ax1+bx+cx2R(x)=\frac{1+ax}{1+bx+cx^2}

where aa, bb and cc are constants. The coefficients of xx, x2x^2 and x3x^3 in the Maclaurin series for R(x)R(x) are to match those of exe^x.

A
I.

Find the Maclaurin series for (1+bx+cx2)1(1+bx+cx^2)^{-1} up to and including the term in x3x^3.

[3]
II.

Hence show that a=13a=\dfrac13, b=23b=-\dfrac23 and c=16c=\dfrac16.

[3]
B

Use R(1)R(1) to approximate ee.

[2]
C

Compare the percentage error of this approximation with that of the third-degree Maclaurin polynomial for exe^x at x=1x=1.

[2]
Question 55
HL • Paper 2
Hard
Calculator Permitted
HL • Paper 2
Hard
Calculator Permitted

A function yy is represented by a Maclaurin series and satisfies

xy+y+xy=0xy''+y'+xy=0

with y(0)=1y(0)=1. Assume that y(0)=0y'(0)=0.

A
I.

Let y=a0+a1x+a2x2+y=a_0+a_1x+a_2x^2+ \cdots. Show that a1=0a_1=0 and that, for n1n\ge 1,

(n+1)2an+1+an1=0(n+1)^2a_{n+1}+a_{n-1}=0
[3]
II.

Hence find the Maclaurin series for yy up to and including the term in x8x^8.

[3]
B

Using this polynomial approximation, estimate the first positive zero of yy.

[2]
C

Explain why the approximation in part (b) should be treated with caution.

[2]
Question 56
HL • Paper 3
Hard
Calculator Permitted
HL • Paper 3
Hard
Calculator Permitted

A function yy satisfies the differential equation y+xy3y=0y''+xy'-3y=0 with y(0)=1y(0)=1 and y(0)=2y'(0)=2. Let y=n=0anxny=\sum_{n=0}^{\infty}a_nx^n

A
I.

Show that an+2=3n(n+2)(n+1)ana_{n+2}=\frac{3-n}{(n+2)(n+1)}a_n for n0n\ge0.

[3]
II.

Hence find the Maclaurin series for yy up to and including the term in x6x^6.

[2]
B

Use your series to estimate y(0.4)y(0.4).

[1]
C

Prove that all odd-power coefficients after a3a_3 are zero.

[3]
Question 57
HL • Paper 3
Hard
Calculator Permitted
HL • Paper 3
Hard
Calculator Permitted

For x0x\ne0, define F(x)=ln(1+x2)x2F(x)=\frac{\ln(1+x^2)}{x^2} and define F(0)F(0) by continuity. The integral I=00.8F(x)dxI=\int_0^{0.8}F(x)\,\mathrm{d}x is to be estimated using a Maclaurin series.

A
I.

Find the Maclaurin series for F(x)F(x).

[2]
II.

Use the first three non-zero terms to estimate II.

[2]
B

The integrated series is alternating for 0x0.80\le x\le0.8. Determine the minimum number of terms of the series for F(x)F(x) that must be integrated so that the alternating-series error bound for II is less than 10410^{-4}.

[4]
Question 58
HL • Paper 3
Hard
Calculator Permitted
HL • Paper 3
Hard
Calculator Permitted

A function yy satisfies y=xyy''=xy with y(0)=1y(0)=1 and y(0)=1y'(0)=-1. Let y=n=0anxny=\sum_{n=0}^{\infty}a_nx^n

A
I.

Find a recurrence relation for the coefficients ana_n.

[3]
II.

Find the Maclaurin series for yy up to and including the term in x6x^6.

[2]
B

Use your series to estimate y(1)y(1).

[1]
C

Prove that a3k+2=0a_{3k+2}=0 for all integers k0k\ge0.

[2]
Question 59
HL • Paper 3
Hard
Calculator Permitted
HL • Paper 3
Hard
Calculator Permitted

The function D(x)=ex20xet2dtD(x)=e^{-x^2}\int_0^x e^{t^2}\,\mathrm{d}t occurs in a model of diffusion. Its Maclaurin series may be found using products of series.

A
I.

Find the Maclaurin series for 0xet2dt\int_0^x e^{t^2}\,\mathrm{d}t up to and including the term in x7x^7.

[2]
II.

Hence find the Maclaurin series for D(x)D(x) up to and including the term in x7x^7.

[3]
B

Use the series from part (a) to estimate D(0.5)D(0.5).

[1]
C

Show that DD satisfies the differential equation D=12xDD'=1-2xD, and use this equation to verify the coefficient of x7x^7 in your series.

[3]
Question 60
HL • Paper 3
Hard
Calculator Permitted
HL • Paper 3
Hard
Calculator Permitted

For x0x\ne0, define L(x)=ln(sinxx)L(x)=\ln\left(\frac{\sin x}{x}\right) with L(0)L(0) defined by continuity. This function is used to study the central peak of a wave pattern.

Even curve of L(x)=ln(sin x/x) near x=0.
A
I.

Show that sinxx=1x26+x4120x65040+\frac{\sin x}{x}=1-\frac{x^2}{6}+\frac{x^4}{120}-\frac{x^6}{5040}+\cdots

[2]
II.

Hence find the Maclaurin series for L(x)L(x) up to and including the term in x6x^6.

[3]
B

Use your answer to part (a) to estimate the positive value of xx for which sinxx=0.95\frac{\sin x}{x}=0.95.

[2]
C

Explain why the Maclaurin series for L(x)L(x) contains only even powers of xx.

[1]

Kinematics