Question

If y is directly proportional to x^2 and y = 36, when x=3 work out a formula connecting y & x ?

Answer 1

`y=4x^2`

Explanation:

If `y` is directly proportional to `x^2`
then there is a constant `c` such that
`y= c * x^2`

If `y=36, x=3` is a solution to this equation
`36 = c * 3^2 = 9c`

`rarr c=4`

So the equation is
`y=4 * x^2`