SOLUTION: How do you factor x^4-84? I'm not sure how you break it up when the x is in 4th power.

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Question 896525: How do you factor
x^4-84? I'm not sure how you break it up when the x is in 4th power.
Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
Factor x^4-84 the same as x^2-y^2=(x-y)*(x+y)
It isn't as neat and pretty though
(x^2-2sqrt(21))*(x^2+2sqrt(21))
(x-sqrt(2)21^(1/4))*(x+sqrt(2)21^(1/4))*(x^2+2sqrt(21))

%28x%5E2-2sqrt%2821%29%29%2A%28x%5E2%2B2sqrt%2821%29%29