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Question 42 Marks
If $2^x=3^y=12^z$, show that : $\frac{1}{z}=\frac{1}{y}+\frac{2}{x}$.
Answer
Hint. Let $2^x=3^y=12^z=k$. Then, $2=k^{\frac{1}{x}}, 3=k^{\frac{1}{y}}$ and $12=k^{\frac{1}{x}}$.
Now, $12=2^2 \times 3 \Rightarrow k^{\frac{1}{x}}=\left(k^{\frac{1}{x}}\right)^2 \times\left(k^{\frac{1}{y}}\right) \Rightarrow k^{\frac{1}{x}}=k^{\left(\frac{2}{x}+\frac{1}{y}\right)}$
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Question 52 Marks
Solve for n : \[\left(3^n \times 9^{n+1}\right) \div\left(3^{n-1} \times 27^{n-1}\right)=81\]
Answer
$n=2$
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Question 302 Marks
Simplify : $\left(x^{\frac{1}{3}}-x^{-\frac{1}{3}}\right)\left(x^{2 / 3}+1+x^{-2 / 3}\right)$
Answer
$\left(x-\frac{1}{x}\right)$
$\begin{aligned}\text { [Hint. Given Exp. }& =(a-b)\left(a^2+a b+b^2\right) \\ & \left.=\left(a^3-b^3\right)\right]\end{aligned}$
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Question 322 Marks
Simplify : $\frac{5 \times(25)^{n+1}-25 \times 5^{2 n}}{5 \times 5^{(2 n+3)}-(25)^{n+1}}$
Answer
$\frac{1}{6}$
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Question 362 Marks
If $(x-1)^{1 / 2}+(y-2)^{1 / 2}+(z-3)^{1 / 2}=0$, then find the values of $x, y$ and $z$.
Answer
1, 2, 3
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Question 372 Marks
If you raise a number to a negative power, can the resulting number be greater than the original number. Justify your answer by giving suitable examples.
Answer
Yes, if the base is a fraction between o and 1.
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