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A-Level CAIE Mathematics A23.6 Numerical solution of equationsQuestion Bank

Question 3

Question 3(i)

(a)

By sketching suitable graphs, show that the equation e12x=4x2\mathrm{e}^{-\frac{1}{2} x}=4-x^{2} has one positive root and one negative root.

[ 2 ]

Question 3(ii)

(b)

Verify by calculation that the negative root lies between -1 and -1.5 .

[ 2 ]

Question 3(iii)

(c)

Use the iterative formula xn+1=(4e12xn)x_{n+1}=-\sqrt{ }\left(4-e^{-\frac{1}{2} x_{n}}\right) to determine this root correct to 2 decimal places. Give the result of each iteration to 4 decimal places.

[ 3 ]

Question 3

[Maximum number: 6]

The equation x53x3+x24=0x^{5}-3 x^{3}+x^{2}-4=0 has one positive root.

Question 3(i)

(a)

Verify by calculation that this root lies between 1 and 2 .

[ 2 ]

Question 3(ii)

(b)

Show that the equation can be rearranged in the form

x=(33x+4x21)\left.x=\sqrt[3]{( } 3 x+\frac{4}{x^{2}}-1\right)
[ 1 ]

Question 3(iii)

(c)

Use an iterative formula based on this rearrangement to determine the positive root correct to 2 decimal places. Give the result of each iteration to 4 decimal places.

[ 3 ]

Question 4

Question 4(b)

(a)

Show by calculation that α\alpha lies between 0.36 and 0.37 .

[ 2 ]

Question 4(c)

(b)

Use the iterative formula xn+1=15(7e12xn)x_{n+1}=\frac{1}{5}\left(7-\mathrm{e}^{-\frac{1}{2} x_{n}}\right) to find β\beta correct to 4 significant figures. Give the result of each iteration to 6 significant figures.

[ 3 ]

Question 4

[Maximum number: 2]

A curve has parametric equations

x=t2+3t+1,y=t4+1x=t^{2}+3 t+1, \quad y=t^{4}+1

The point P on the curve has parameter p. It is given that the gradient of the curve at P is 4 .

Question 4(ii)

(a)

Verify by calculation that the value of p lies between 1.8 and 2.0.

[ 2 ]

Question 4(iii)

(b)

Use an iterative formula based on the equation in part (i) to find the value of p correct to 2 decimal places. Give the result of each iteration to 4 decimal places.

Question 4

Question 4(i)

(a)

By sketching suitable graphs, show that the equation

4x21=cotx4 x^{2}-1=\cot x

has only one root in the interval 0<x<12π0<x<\frac{1}{2} \pi.

[ 2 ]

Question 4(ii)

(b)

Verify by calculation that this root lies between 0.6 and 1 .

[ 2 ]

Question 4(iii)

(c)

Use the iterative formula

xn+1=12(1+cotxn)x_{n+1}=\frac{1}{2} \sqrt{ }\left(1+\cot x_{n}\right)

to determine the root correct to 2 decimal places. Give the result of each iteration to 4 decimal places.

[ 3 ]

Question 3

Question 3(a)

(a)

By sketching a suitable pair of graphs, show that the equation secx=212x\sec x=2-\frac{1}{2} x has exactly one root in the interval 0x<12π0 \leqslant x<\frac{1}{2} \pi.

[ 2 ]

Question 3(b)

(b)

Verify by calculation that this root lies between 0.8 and 1 .

[ 2 ]

Question 3(c)

(c)

Use the iterative formula xn+1=cos1(24xn)x_{n+1}=\cos ^{-1}\left(\frac{2}{4-x_{n}}\right) to determine the root correct to 2 decimal places. Give the result of each iteration to 4 decimal places.

[ 3 ]

Question 5

Question 5(b)

(a)

The sequence of values given by the iterative formula

xn+1=πsin1(1e12xn+1),x_{n+1}=\pi-\sin ^{-1}\left(\frac{1}{\mathrm{e}^{-\frac{1}{2} x_{n}}+1}\right),

with initial value x1=2x_{1}=2, converges to one of these roots.
Use the formula to determine this root correct to 2 decimal places. Give the result of each iteration to 4 decimal places.

[ 3 ]

Question 5

[Maximum number: 3]
Question image

The diagram shows the part of the curve y=x2cos3xy=x^{2} \cos 3 x for 0x16π0 \leqslant x \leqslant \frac{1}{6} \pi, and its maximum point M, where x=a.

Question 5(b)

(a)

Use an iterative formula based on the equation in (a) to determine a correct to 2 decimal places. Give the result of each iteration to 4 decimal places.

[ 3 ]

Question 5

[Maximum number: 5]

The curve with equation

y=5e2x8x220y=5 \mathrm{e}^{2 x}-8 x^{2}-20

crosses the x-axis at only one point. This point has coordinates (p, 0).

Question 5(ii)

(a)

Show by calculation that 0.75<p<0.85.

[ 2 ]

Question 5(iii)

(b)

Use an iterative formula based on the equation in part (i) to find the value of p correct to 5 significant figures. Give the result of each iteration to 7 significant figures.

[ 3 ]

Question 4

[Maximum number: 3]
Question image

The diagram shows a semicircle A C B with centre O and radius r. The tangent at C meets A B produced at T. The angle B O C is x radians. The area of the shaded region is equal to the area of the semicircle.

Question 4(ii)

(a)

Use the iterative formula xn+1=tan1(xn+π)x_{n+1}=\tan ^{-1}\left(x_{n}+\pi\right) to determine x correct to 2 decimal places. Give the result of each iteration to 4 decimal places.

[ 3 ]
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