Question 721421
Solve the following equation using the substitution method. 
x^4 –5x^2 –14=0
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Let u = x^2; then substitute:
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u^2 -5u -14 = 0
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Factor:
(u-7)(u+2) = 0
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u = 7 or u = -2
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Solve for "x":
x^2 = 7 or x^2 = -2
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x = +-sqrt(7) or x = +-i*sqrt(2)
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Cheers,
Stan H.
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