Explicație pas cu pas:
-x²+2x+3=-x²-x+3x+3=-x(x+1)+3(x+1)=(x+1)(3-x)
x²-9=(x+3)(x-3)=-(3-x)(x+3)
-x²+2x+3/x²-9=(x+1)(3-x)/-(3-x)(x+3)=
x+1/-(x+3)
