Question

y varies directly as the square of x. When x = 2, y = 20. Find y when x = 4

Answer 1

y=Rx^2 where R is a constant. When x=2, y=20, so solve for R

Answer 2

r=5

Answer 3

Okay, so your equation is
y=5x^2
Now you want to calculate for y when x=4.