-- (x² - 3x +2) /(x² - 1 ) = (x-1)(x-2)/(x+1)(x-1) = (x-2) / (x+1) x∈R / {-1}
-- (x³ -x² +5x - 5) / (x³ - x² -2x+2) = [x² (x-1) +5(x-1)] / [x²(x-1) - 2(x-1)] =
=(x-1)(x² +5) / (x-1)(x² - 2) =(x² + 5) / (x² - 2) x∈ R / { √2, -√2}
-- 2/ (x² - 9) + 1/(x-3) + (x+5) / x² - 9) = (2+ x+3 +x+5) / (x+3)(x-3) =
= (2x + 10)/(x+3)(x-3) = 2(x+5) / (x+3)(x-3)
deoarece intr-o fractie numitorul trebuie sa fie ≠ 0 ⇒ x-3≠0 x≠3
x+3 ≠0 x≠ - 3 ⇒ x ∈ R / {-3, +3}