Question

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

Answer 1

Hi,

Explanation:

a varies directly as the square of b:

`a=k*b^2\\if\ a=5,then\ b=2\\5=k*2^2\ \Longrightarrow\ k=(5)/(4) \\\\When\ b=3\ then\\\\a=(5)/(4)*3^2\\\\\boxed{a=(45)/(4) }\\`