Question 224463
{{{x^4+7x^2-8=0}}}


{{{x^4+7x^2-8=(x^2+8)*(x^2-1)=0}}}


{{{x^2+8=0}}} and {{{x^2-1=0}}}


{{{x^2=-8}}} and {{{x^2=1}}}


Take the square root to both sides of the equation


{{{x1=i*2sqrt(2)}}}  where {{{i=sqrt(-1)}}}
{{{x2=-i*2sqrt(2)}}}
{{{x3=1}}}
{{{x4=-1}}}


ANSWER:  The solutions are:  {{{x1=i*2sqrt(2)}}}, {{{x2=-i*2sqrt(2)}}}, {{{x3=1}}} and {{{x4=-1}}}


I hope the above steps were helpful.


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Good luck in your studies!


Respectfully,
Dr J