Yvaries directly as x squared. y is 18 when x is 3. find y if x is 4. any ?

Step-by-step 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

area = length x width

length = 2 x width

32 = 2 x width x width

32 = 2 x width^2

36 = width ^2  

width = 6

length = 12

area is 32

perimeter = 2 x 12 + 2 x 6 = 24 + 12 = 36

step-by-step explanation: