SOLUTION: Solve the following polynomial equation. If needed, write your answer as a fraction reduced to lowest terms. y^4 + 8y^2 -9 = 0 I'd like to know the steps to completing

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Solve the following polynomial equation. If needed, write your answer as a fraction reduced to lowest terms. y^4 + 8y^2 -9 = 0 I'd like to know the steps to completing      Log On


   

Question 505319: Solve the following polynomial equation. If needed, write your answer as a fraction reduced to lowest terms.
y^4 + 8y^2 -9 = 0

I'd like to know the steps to completing this. Can this be factored? How do I make it ready to be plugged into the quadratic formula? Any help is appreciated. Thanks in advance.
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
y^4 + 8y^2 -9 = 0
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Factor:
y^4 + 9y^2-y^2 -9 = 0
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y^2(y^2+9) -(y^2+9) = 0
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Factor:
(y^2+9)(y^2-1) = 0
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Factor:
(y^2+9)(y-1)(y+1) = 0
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y = 3i or y = -3i or y = 1 or y = -1
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Cheers,
Stan H.
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