Question

y varies directly as the square of x. When x = 4, y = 32. Find x when y = 18.

Answer 1

So we know that
y = kx^2 for some constant k

We also know that when x = 4, y = 32

Hence substituting into that equation we have

32 = k.4^2 i.e., 32 = 16k.

So now you can find k.

Can you now do the second part yourself?