SOLUTION: I am lost, here is the question... y varies directly as the square of x. If y=162 when r=9, find y when r=3

Question 438125: I am lost, here is the question... y varies directly as the square of x. If y=162 when r=9, find y when r=3
Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
If you mean it varies with r:
--------
y = k/r^2
You can find the constant
162 = k*(9^2) = k*81
k = 2
----------
at r=3, y = 2*3^2
y = 18
------------
You don't have to find the constant
at r = 3, y = 162/(9/3)^2 = 162/9 = 18
r is 1/3, so y is (1/3)^2 of 162
= 18

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