SOLUTION: x2-21=4x

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Question 291859: x2-21=4x
Answer by checkley77(12844) About Me  (Show Source):
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x^2-21=4x
x^2-4x-21=0
(x-7)(x+3)=0
x-7=0
x=7 ans.
x+3=0
x=-3 ans.