6x + 1 ≠ 0 ⇒ x≠ - 1/6 este o fractie subunitara x I -∞ -1/6 ∞ ---------------I---------------------------------------------------------------------------------------------------- f(x) I 0 +∞ I -∞ 0 mc mc f(0) =-5 daca se calculeaza si f' >0 si nu are radacini