SOLUTION: x^4+3x^2-4=0

Question 27082: x^4+3x^2-4=0
Answer by tran3209(100) (Show Source): You can put this solution on YOUR website!
X^4+3X^2-4=0
let Y=X^2, replace X^2 by Y in the equation

Y^2+3Y-4=0
(Y+4)(Y-1)=0

Y+4=0---Y=-4 0r Y=4(-1) replace -1 by i^2---> Y=4i^2--->replace Y by X^2
X^2=4i^2---> X=+ / - square root of 4i^2 ---> X=+2i and X=-2i
Y-1=0 replace Y by X^2--->X^2=1---> X=+ / - square root of 1---> x=+1 and x=-1
The answers are X=+2i, X=-2i, X=+1 and X=-1
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