Question

Let y vary inversely as the second power of x. If x doubles, what happens to y?

Answer 1

y vary inversely as the second power of x

y=k/x^2, where k is any constant
k = x^2 y

x doubles, so x becomes 2x
k = (2x)^2 y = 4x^2y

y=k/x^2 becomes y = 4x^2y / x^2 = 4y

y quadruples.