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| Question 1017893:  if x^4 = x^2 - 72 find x
 Answer by fractalier(6550)
      (Show Source): 
You can put this solution on YOUR website! We can transform x^4 = x^2 - 72
 into
 x^4 - x^2 + 72 = 0
 Now let
 y = x^2
 and we get
 y^2 - y + 72 = 0
 which is not factorable.
 Are you sure this correct?
 You sure the problem didn't say +72 above?
 If this is indeed correct, apply the quadratic formula and then take the square root of each of your roots for y, yielding four solutions.
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