SOLUTION: solve. w^4-4w^2-2=0 what is the solution. W= (type an exact answer using radicals if needed, use commas to seperate answers

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Question 309511: solve.
w^4-4w^2-2=0
what is the solution.
W=
(type an exact answer using radicals if needed, use commas to seperate answers
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Use a substitution, u=w%5E2, then u%5E2=w%5E4
w%5E4-4w%5E2-2=0
u%5E2-4u-2=0
Complete the square.
u%5E2-4u%2B4-2=4
%28u-2%29%5E2-2=4
%28u-2%29%5E2=6
u-2=0+%2B-+sqrt%286%29
u=-2+%2B-+sqrt%286%29
w%5E2=-2%2B-+sqrt%286%29
w=0+%2B-+sqrt%28-2+%2B-+sqrt%286%29%29
Two real roots, two complex roots.
+graph%28+300%2C+300%2C+-3%2C+3%2C+-10%2C+10%2Cx%5E4-4x%5E2-2%29+