SOLUTION: Find the solution set for x^2-21=4x

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Question 89205: Find the solution set for
x^2-21=4x
Answer by Nate(3500) About Me  (Show Source):
You can put this solution on YOUR website!
x^2 - 21 = 4x
x^2 - 4x - 21 = 0
x^2 - 7x + 3x - 21 = 0
(x^2 - 7x) + (3x - 21) = 0
x(x - 7) + 3(x - 7) = 0
(x + 3)(x - 7) = 0
x = -3 and 7