y∈Im f ⇔ exista x∈R\{1} astfel incat f(x)=y
(x²-5x+6)/(x²-2x+1) = y
x²-5x+6 = y*(x²-2x+1)
x²-5x+6 = yx²-2yx+y
(y-1)x²-(2y-5)x+(y-6) = 0 ecuatia are solutii reale ⇔ Δ≥0
Δ = (2y-5)²-4(y-1)(y-6) = 4y²-20y+25-4y²+28y-24 = 8y+1 ≥ 0 ⇒ 8y ≥ -1 ⇒ y ≥ -1/8
Im f = [-1/8, +∞)
