Question

$p$ is inversely propotional to the square of $(q+4)$. When $p=2,q=2$. When $q=-2$, then $p$ is .

• A. $-18$
• B. $16$
• C. $18$

Answer 1

The correct option is C $18$

Given that $p$ $\propto$ $\frac{1}{(q+4{)}^2}$

$p=\frac{k}{(q+4{)}^2}$
Given : $p=2,q=2$

$\Rightarrow 2=\frac{k}{(2+4{)}^2}$

$\Rightarrow k=2\times (q+4{)}^2=72$

$\Rightarrow p=\frac{72}{(q+4{)}^2}$

Now, when $q=-2$

$\Rightarrow p=\frac{72}{(2{)}^2}=\frac{72}{4}=18$