Question

y varies directly as the square of x. When x = 1, y = 3. What is the value of y when x = 3?
1
9
27
81

Answer 1

if its a direct variation, what does the equation relating x and y look like?

Answer 2

do i add both x & y ? idk how to do it

Answer 3

y = kx^2
3 = k*1 so
y = 3x^2
when x = 3
y = 27

Answer 4

well, in general, a direct variation looks like:
y = kx

In this case, we have "y varies directly as the SQUARE of x"
so, y = kx^2 would suit this problem nicely

Answer 5

..yeah, that's correct. :P