SOLUTION: solve by making a u-substitution. x^4-84x^2+320=0

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Question 964320: solve by making a u-substitution. x^4-84x^2+320=0
Answer by checkley77(12844) About Me  (Show Source):
You can put this solution on YOUR website!
FACTORS OF 320 THAT TOTAL 84?
320/2=160 TOO BIG.
320/4=80 LOOKS GOOD
80+4=64
(x-80)(X-4) ANS.