Question 201889
{{{x^4-13x^2+36=0}}}
(x^2-9)(x^2-4)=0
(x+3)(x-3)(x+2)(x-2)=0
x+3=0
x=-3 ans.
x-3=0
x=3 ans.
x+2=0
x=-2 ans.
x-2=0
x=2 ans.