Direct variation is y = kx, where k is the constant of variation.
But now it says y varies directly with x2 (or 2x), so now the x in the equation is 2x.
The equation is y = k(2x)
Now you find k.
y = 96 when x = 4.
(96) = k(2*4)
96 = k(8)
k = 12
The equation is now y = 12(2x)
To find the value of y when x=2, plug 2 into the equation you made.
y = 12(2*2)
y = 48 _________________
Now it's with a "quadratic variation," which is the same thing except x is squared.
The equation is y = kx^2
But y varies directly with x2 (same thing as 2x), so now it's y = k(2x)^2.
Now you find k by substituting y and x values that were given.
y = 180 when x = 6
(180) = k(2*6)^2
180 = k(12)^2
180 = k(144)
k = 1.25
k, 1.25, is the constant of variation.
