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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!

 
 Jan 7, 2019
 #1
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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

 Jan 8, 2019

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