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A-Level CAIE Mathematics A23.2 Logarithmic and exponential functionsQuestion Bank

[Maximum number: 4]

Use logarithms to solve the equation 43x1=3(5x)4^{3 x-1}=3\left(5^{x}\right), giving your answer correct to 3 decimal places.

[Maximum number: 3]

Given that 2y=93x2^{y}=9^{3 x}, use logarithms to show that y=k x and find the value of k correct to 3 significant figures.

[Maximum number: 3]

Given that ln(1+e2y)=x\ln \left(1+\mathrm{e}^{2 y}\right)=x, express y in terms of x.

[Maximum number: 4]

Use logarithms to solve the equation 52x1=2(3x)5^{2 x-1}=2\left(3^{x}\right), giving your answer correct to 3 significant figures.

[Maximum number: 3]

Using the substitution u=exu=\mathrm{e}^{x}, or otherwise, solve the equation

ex=1+6ex\mathrm{e}^{x}=1+6 \mathrm{e}^{-x}

giving your answer correct to 3 significant figures.

[Maximum number: 4]
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The variables x and y satisfy the equation y=42xay=4^{2 x-a}, where a is an integer. As shown in the diagram, the graph of lny\ln y against x is a straight line passing through the point (0,-20.8), where the second coordinate is given correct to 3 significant figures.

(a)

Show that the gradient of the straight line is ln16\ln 16.

[ 2 ]
(b)

Determine the value of a.

[ 2 ]

Solve the equation log10(x+9)=2+log10x\log _{10}(x+9)=2+\log _{10} x.

[Maximum number: 3]

Solve the equation ln(x33)=3lnxln3\ln \left(x^{3}-3\right)=3 \ln x-\ln 3. Give your answer correct to 3 significant figures.

[Maximum number: 3]

Solve the equation 3x+23x2=8\frac{3^{x}+2}{3^{x}-2}=8, giving your answer correct to 3 decimal places.

[Maximum number: 5]

Showing all necessary working, solve the equation 52x=5x+55^{2 x}=5^{x}+5. Give your answer correct to 3 decimal places.

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