Question

Y varies directly as x squared. y is 18 when x is 3. Find y if x is 4. Any help? thanks ​

Answer 1

Explanation:

y ∝ x^2

Introducing the proportionality constant, we have

y = kx^2

Given : y= 18 when x = 3

substitute the given values in order to get the constant

i.e 18 = k x 3^2

18 = 9k

k = 2

therefore the formula connecting x and y

⇒ y = 2x^2

To find y if x is 4, just substitute x = 4 into the formula connecting x and y

i.e y = 2 x 4^2

= 2 x 16

= 32