x^2-6)*(x^2+2)=(x^2-2)^2-x
x^4-4x^2-12-(x^2-2)^2+x=0
x^4-4x^2-12-(x^4-4x^2+4)+x=0
x^4-4x^2-12-x^4+4x^2-4+x=0
-4x^2-12+4x^2-4+x=0
-12-4+x=0
-16+x=0
x=16
x^2-6)*(x^2+2)=(x^2-2)^2-x
x^4-4x^2-12-(x^2-2)^2+x=0
x^4-4x^2-12-(x^4-4x^2+4)+x=0
x^4-4x^2-12-x^4+4x^2-4+x=0
-4x^2-12+4x^2-4+x=0
-12-4+x=0
-16+x=0
x=16