Question

The value of y varies directly with x^2, and y = 36 when x = 3.

What is the value of y when x = 5?

i think 60

Answer 1

@jabez177 @TheSmartOne

Answer 2

There's a constant of variation k.
You may remember y = kx.
Do you know what k is in your example?

Answer 3

i never learned y = kx

Answer 4

In this case

y = kx^2

plug in y = 36
x = 3

and solve for k

Answer 5

36 = k x 9

Answer 6

and k = ?

Answer 7

well 36 divided by 9 = 4

Answer 8

so is the answer 20?

Answer 9

y = 4x^2

now plug in x = 5 and solve for y

Answer 10

100?

Answer 11

and that's your answer

Answer 12

okay