Question

Write the quadratic variation equation for the relationship: y varies directly with x2 and y = 36 when x = 3.

A. y = ¼x^2

B. y = 12x

C. y = 4x^2

D. y = x^2 + 25

Answer 1

I think its B

Answer 2

sub 3 into each of the ones with x^2 in it, what comes up with 36?

Answer 3

the standard formula for directly related is:

y = kx

in this case they want

y = kx^2

so if x = 3 and y = 36 then

36 = k (3)^2

now solve for k

divide the 9

k = 36/9

k = 4

therefore

y = 4x^2