y is inversely proportional to d^2

when d = 5, y = 20

d is directly proportional to x^2

when x = 4, d = 80

find a formula for y in terms of x.

give your answer in its simplest form.

thank you!

Guest Jan 7, 2019

#1**0 **

y = k/d^2

20 = k/(5)^2

k = 500

y= 500/d^2 (1)

x^2 = md

4^2 = m(80)

m= 1/5

d= 5x^2 (2)

Sub 2 in to 1 y = 500/(5x^2)^2 = 20/x^4

ElectricPavlov Jan 8, 2019