Question 635936
 {{{x^4-2x^2-35=0}}}

let x^2=a

{{{a^2-2a-35=0}}}

{{{a^2-7a+5a-35=0}}}

{{{a(a-7)+5(a-7)=0}}}

{{{(a-7)(a+5)=0}}}

a= 7 OR a=-5

resubstitute a
{{{x^2= 7 OR x^2= -5}}}
{{{x^2=7}}}
x= +- (sqrt(7))

{{{x^2=5}}}

x^2= -1*5

x= +-(sqrt(-1) * sqrt(5))

x= +- (sqrt(5) i)

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