x^2+2x=x^2+2x+1-1=(x+1)^2-1
∫^(-3)_(- ∞ )dx/(x^2+2x)= ∫^(-3)_(- ∞ )dx/((x+1)^2-1)=
=(1/2)ln|(x+1-1)/(x+1+1)|^(-3)_(- ∞ )=
=(1/2)ln|(-3)/(-3+2)|- (1/2) lim_(A → - ∞ )ln|(A+1-1)/(A+1+1)|=
=(1/2)ln3 - (1/2) lnlim_(A → - ∞ )|(A/(A+2)|=
=(1/2)ln3-(1/2)ln1=
=(1/2)ln3-0= (1/2) ln3 - сходится