SOLUTION: (x^2)^2-7x^2-8=0

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Question 269533: (x^2)^2-7x^2-8=0
Answer by drk(1908) About Me  (Show Source):
You can put this solution on YOUR website!
Let Y = x^2 and Y^2 = x^4. We get
Y^2 - 7Y - 8 = 0
factoring, we get
(Y-8)(Y+1) = 0
solving each for Y, we get
Y = 8 and
Y = -1
re-substitute x^2 for Y and we get
x^2 = 8 - - - > X = 2sqrt(2)
x^2 = -1 - - -> no solution