x=(x^2-4x+2)/√(x^2-8x+12)
x√(x^2-8x+12)=(x^2-4x+2)
x^2(x^2-8x+12)=(x^2-4x+2)^2
x^4-8x^3+12x^2=x^4+16x^2+4-8x^3+4x^2- 16x
12x^2=16x^2+4+4x^2- 16x
8x^2+4- 16x =0
2x^2- 4x +1=0
x=(4±√16- 8)/ 4
x=(2±√2 ) /2
x1=(2+√2 ) /2 , x2=(2- √2 ) /2