SOLUTION: find all zeroes f(x) = x^4+6x^2-27

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Question 310460: find all zeroes f(x) = x^4+6x^2-27
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Let u=x%5E2, then u%5E2=x%5E4
+x%5E4%2B6x%5E2-27=0
+u%5E2%2B6u-27=0
Factor.
%28u%2B9%29%28u-3%29
Two solutions:
u%2B9=0
u=-9
x%5E2=-9
x=0+%2B-+3i
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.
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u-3=0
u=3
x%5E2=3
x=0+%2B-+sqrt%283%29
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.
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(-sqrt%283%29,sqrt%283%29,-3i, 3i)