Given x^4+95x^2-500=0
set u=x^2, and substitute
u^2+95u-500=0
Since -5*100=-500, and -5+100=95, we factor equation as
(u-5)(u+100)=0
=> u=5 or u=-100
Back-substitute,
u=5 => x= ± √ 5
u=-100 => x= ± 10i (if you work with complex roots)
So
answer: the real roots of given equation are ± √ 5
the complext roots are: x= ± 10i
