Question

If y is directly proportional to x^2 and y =9 when x =2, what is y when x=4

Answer 1

" y is directly proportional to x^2"
y=k x^2
'y =9 when x =2"
9= k (2)^2
9=4k
k=9/4

what is y when x=4?

Answer 2

would I multiply 9*4? 36?

Answer 3

basically, after simplifying that 9/4 * 4^2 is same as 9*4.
Correct.