x^4-33x^2+200=0 (factor that out)
x^4-33x^2+200 -----> (x^2-8)(x^2-25)
new equation:
x^2-8=0 x^2-25=0 (solve for x for both equations)
x^2=8 x^2 =25
the x's are still squared so you have the square root both sides of the equations to get rid of the ^2:
x^2=8 x^2=25
[tex] \sqrt{ x^{2} } = \sqrt{8} [/tex] [tex] \sqrt{x ^{2} } = \sqrt{25} [/tex]
x=[tex]2 \sqrt{2} [/tex] x=5