SOLUTION: Solve by completing the square: x^4-5x^2-36=0

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Question 92781: Solve by completing the square:
x^4-5x^2-36=0
Answer by checkley75(3666) About Me  (Show Source):
You can put this solution on YOUR website!
X^4-5X^2-36=0
X^4-5X^2+6.25=36+6.25
(X^2-2.5)(X^2-2.5)=42.25
(X^2-2.5)^2=42.25
X^2-2.5=SQRT42.25
X^2-2.5=6.5
X^2-2.5-6.5=0
(X^2-9)=0
(X-3)(X+3)=0
X-3=0
X=3 ANSWER.
X+3=0
X=-3 ANSWER.