SOLUTION: 7y to the third power minus 28y equals 0

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Question 403036: 7y to the third power minus 28y equals 0
Answer by jsmallt9(3758) About Me  (Show Source):
You can put this solution on YOUR website!
7y%5E3-28y=0
We start by factoring. And factoring starts with the Greastest Common Facotr (GCF). The GCF here is 7y:
7y%28y%5E2-4%29=0
The second factor is a difference of squares so we can use the pattern a%5E2-b%5E2=%28a%2Bb%29%28a-b%29 with "a" being y and "b" being 2:
7y(y+2)(y-2) = 0
From the Zero Product Property we know that this (or any) product can be zero only if one (or more) of the factors is zero. So:
7y = 0 or y+2 = 0 or y-2 = 0
Solving each of these we get:
y = 0 or y = -2 or y = 2
These are the three solutions to your equation.