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A-Level CAIE Mathematics AS2.6 Numerical solution of equationsQuestion Bank

Question 1

[Maximum number: 5]

The sequence of values given by the iterative formula

xn+1=4xn2+2xn3,x_{n+1}=\frac{4}{x_{n}^{2}}+\frac{2 x_{n}}{3},

with initial value x1=2x_{1}=2, converges to α\alpha.

Question 1(i)

(a)

Use this iterative formula to find α\alpha correct to 3 decimal places. Give the result of each iteration to 5 decimal places.

[ 3 ]

Question 1(ii)

(b)

State an equation that is satisfied by α\alpha, and hence find the exact value of α\alpha.

[ 2 ]

Question 2

[Maximum number: 3]
Question image

In the diagram, A B C is a triangle in which angle A B C is a right angle and B C=a. A circular arc, with centre C and radius a, joins B and the point M on A C. The angle A C B is θ\theta radians. The area of the sector C M B is equal to one third of the area of the triangle A B C.

Question 2(ii)

(a)

This equation has one root in the interval 0<θ<12π0<\theta<\frac{1}{2} \pi. Use the iterative formula

θn+1=tan1(3θn)\theta_{n+1}=\tan ^{-1}\left(3 \theta_{n}\right)

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

[ 3 ]

Question 2

[Maximum number: 5]

The sequence of values given by the iterative formula

xn+1=xn(xn3+100)2(xn3+25),x_{n+1}=\frac{x_{n}\left(x_{n}^{3}+100\right)}{2\left(x_{n}^{3}+25\right)},

with initial value x1=3.5x_{1}=3.5, converges to α\alpha.

Question 2(i)

(a)

Use this formula to calculate α\alpha correct to 4 decimal places, showing the result of each iteration to 6 decimal places.

[ 3 ]

Question 2(ii)

(b)

State an equation satisfied by α\alpha and hence find the exact value of α\alpha.

[ 2 ]

Question 2

[Maximum number: 5]

The sequence of values given by the iterative formula

xn+1=7xn8+52xn4x_{n+1}=\frac{7 x_{n}}{8}+\frac{5}{2 x_{n}^{4}}

with initial value x1=1.7x_{1}=1.7, converges to α\alpha.

Question 2(i)

(a)

Use this iterative formula to determine α\alpha correct to 2 decimal places, giving the result of each iteration to 4 decimal places.

[ 3 ]

Question 2(ii)

(b)

State an equation that is satisfied by α\alpha and hence show that α=205\alpha=\sqrt[5]{20}.

[ 2 ]

Question 2

[Maximum number: 5]
Question image

The diagram shows the curve y=x4+2x9y=x^{4}+2 x-9. The curve cuts the positive x-axis at the point P.

Question 2(i)

(a)

Verify by calculation that the x-coordinate of P lies between 1.5 and 1.6.

[ 2 ]

Question 2(ii)

(b)

Show that the x-coordinate of P satisfies the equation

x=(9x2).3x=\sqrt[3]{\left(\frac{9}{x}-2\right) .}

Question 2(iii)

(c)

Use the iterative formula

xn+1=(9xn2)3x_{n+1}=\sqrt[3]{\left(\frac{9}{x_{n}}-2\right)}

to determine the x-coordinate of P correct to 2 decimal places. Give the result of each iteration to 4 decimal places.

[ 3 ]

Question 3

[Maximum number: 3]

It is given that 0a(3e2x1)dx=12\int_{0}^{a}\left(3 \mathrm{e}^{2 x}-1\right) \mathrm{d} x=12, where a is a positive constant.

Question 3(b)

(a)

Use an iterative formula, based on the equation in (a), to find the value of a correct to 4 significant figures. Use an initial value of 1 and give the result of each iteration to 6 significant figures.

[ 3 ]

Question 3

Question 3(i)

(a)

By sketching a suitable pair of graphs, show that the equation x3=3xx^{3}=3-x has exactly one real root.

[ 2 ]

Question 3(ii)

(b)

Show that if a sequence of real values given by the iterative formula

xn+1=2xn3+33xn2+1x_{n+1}=\frac{2 x_{n}^{3}+3}{3 x_{n}^{2}+1}

converges, then it converges to the root of the equation in part (i).

[ 2 ]

Question 3(iii)

(c)

Use this iterative formula to determine the root correct to 3 decimal places. Give the result of each iteration to 5 decimal places.

[ 3 ]

Question 3

Question 3(i)

(a)

By sketching a suitable pair of graphs, show that the equation

x3=112xx^{3}=11-2 x

has exactly one real root.

[ 2 ]

Question 3(ii)

(b)

Use the iterative formula

xn+1=3(112xn)x_{n+1}=\sqrt[3]{ }\left(11-2 x_{n}\right)

to find the root correct to 4 significant figures. Give the result of each iteration to 6 significant figures.

[ 3 ]

Question 4

[Maximum number: 6]

The sequence of values given by the iterative formula

xn+1=2xn2+xn+9(xn+1)2,x_{n+1}=\frac{2 x_{n}^{2}+x_{n}+9}{\left(x_{n}+1\right)^{2}},

with x1=2x_{1}=2, converges to α\alpha.

Question 4(i)

(a)

Find the value of α\alpha correct to 2 decimal places, giving the result of each iteration to 4 decimal places.

[ 3 ]

Question 4(ii)

(b)

Determine the exact value of α\alpha.

[ 3 ]

Question 4

[Maximum number: 3]
Question image

The diagram shows the curve with equation y=5lnx2x+1y=\frac{5 \ln x}{2 x+1}. The curve crosses the x-axis at the point P and has a maximum point M.

Question 4(iii)

(a)

Use an iterative formula based on the equation in part (ii) to find the x-coordinate of M correct to 4 significant figures. Show the result of each iteration to 6 significant figures.

[ 3 ]
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