SOLUTION: Solve the equation in the complex number system. x^4 + 3x^2 - 4 = 0

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Question 1208827: Solve the equation in the complex number system.


x^4 + 3x^2 - 4 = 0
Found 2 solutions by josgarithmetic, timofer:
Answer by josgarithmetic(39616) About Me  (Show Source):
You can put this solution on YOUR website!
First notice that the degree-four expression is factorable.

THIS should help:

%28x%5E2-1%29%28x%5E2%2B4%29=0

Answer by timofer(104) About Me  (Show Source):
You can put this solution on YOUR website!
t=x%5E2

x%5E4%2B3x%5E2-4=0
t%5E2%2B3t-4=0
%28t-1%29%28t%2B4%29=0

t-1=0
t=1
x%5E2=1
x=1 or x=-1

or t%2B4=0
t=-4
t=2i or t=-2i


x can be -1, or 1, or -2i, or 2i.