Question

if a varies directly as the square of b, and a=5 when b=2, find a when b=3

Answer 1

a=5

b=2

then if

a=?

b=3

since

a varies directly as the square of b

$a\rightarrow b^2$

then

$5\rightarrow2^2$$a\rightarrow3^2$

then

$a=\frac{3^2*5}{2^2}$$a=\frac{45}{4}=11.25$

then

a=11.25