Question

y varies directly as the square of x. When x = 3, y = 54. Find y when x = 8.

Answer 1

y = (k)(x^2) from the "When ...", you should be able to determine the value for k by plugging in the x and y.

Answer 2

What'd u get?

Answer 3

What'd YOU get?

Answer 4

nothing yet...

Answer 5

What does your substitution equation look like? Show me your work.

Answer 6

I dont know how to do any of this at all......

Answer 7

Well, I gave you the proportion equation, but should be talked about in itself. Assuming you know how that was derived, y = (k)(x^2), just put the x and y values in. You'll have an equation in one variable which will be very simple to solve. That's the first step. Then, for the second part, you will have k and x, so just tehn solve for y.