1. ## Inverse Proportion

it is know that variable A is inversely proportional to the square of variable B. For a particular value of B, A is 64. When B is doubled, what happens to A?

2. Originally Posted by Punch
it is know that variable A is inversely proportional to the square of variable B. For a particular value of B, A is 64. When B is doubled, what happens to A?
Hi Punch,

write an inverse proportion relationship using fractions

$A=\frac{k}{B^2}$

$64=\frac{k}{B^2}$

if B is doubled...

$\frac{k}{(2B)^2}=\frac{k}{2^2B^2}=\frac{1}{4}\ \frac{k}{B^2}$

hence A is quartered.

3. that was good, thanks