Question 82627
this is a quadratic in (x^2) ... rewriting will help clarify ... (x^2)^2-10(x^2)+9=0


factoring gives ((x^2)-9)((x^2)-1)=0 ... factoring again gives (x+3)(x-3)(x+1)(x-1)=0


so x=-3, x=3, x=-1, x=1