(2x²+x-1)/(2x²+3x+1)=
2x²+x-1=x²+x+x²-1=x(x+1)+(x-1)(x+1)=(x+1)(x+x-1)=(x+1)(2x-1)
2x²+3x+1=x²+2x+1+x²+x=(x+1)²+x(x+1)=(x+1)(x+1+x)=(x+1)(2x+1)
(x+1)(2x-1)/(x+1)(2x+1)
punem conditia ca numitorul sa fie diferit de zero
(x+1)(2x+1)≠0
x+1≠0; x≠-1
2x+1≠0; x≠-1/2
x∈R-{-1; -1/2}=D (domeniu de definitie)
fractia se simplifica prin (x+1)
rezulta = (2x-1)/(2x+1)
