a.) x²+2x/x²-4=x(x+2)/(x-2)(x+2)=x/x-2 deoarece (x+2) se simplifica
b.)x²-36/x²+12x+36=(x-6)(x+6)/(x+6)(x+6) =x-6/x+6 deoarece (x+6) se simplifica
rezolvarea la x²+12x+36
x²+12x+36=0
Δ=b²-4ac=12²-4*1*36=144-144=0
x1=-b-√Δ/2a=-12-0/2=-12/2=-6
x2=-b+√Δ/2a=-12+0/2=-12/2=-6
