Question

y varies directly as the square of x. When x = 5, y = 5. Find y when x = 10.

Answer 1

x^2 is directly proportional to y
so taking "k" as the proportionality constant we get
x^2 = yk
5^2=5k
25=5k
k=5
so when x=10
10^2=yk
100 = 5y
therefore y=20...