Question

y varies directly as the square of x. When x = 3, y = 18. What is the value of y when x = 4?

a. 24
b. 16
c. 32
d. 12

Answer 1

If y varies directly as the square of x, then it is written this way:
\[y=kx^{2}\]
You need to find the value of k using the values given for x and y. Then rewrite the equation above and substitute the value of k in and the NEW value of x. There's another way to do it with proportions, but most students don't like that method.

Answer 2

So 32?

Answer 3

If that's the way it works.

Answer 4

Lol okay thanks