Выделим полный квадрат
x^2+2x=x^2+2x+1-1=(x+1)^2-1
d(x+1)=dx
= ∫ ^(2)_(1)d(x+1)/((x+1)^2-1)=(1/2)ln|(x+1-1)/(x+1+1)|^(2)_(1)=
=(1/2)*(ln(2/4)-ln(1/3))=(1/2)*ln(3/2)
3.
Интегрирование по частям
u=x^2
du=2xdx
dv=x*e^(x^2)dx
v=(1/2)*e^(x^2)
∫x^3*e^(x^2)dx=(x^2/2)*e^(x^2)- ∫x*e^(x^2)dx=
=(x^2/2)*e^(x^2)-(1/2)*e^(x^2).
О т в е т. ∫^(1)_(0)x^3*e^(x^2)dx=((x^2/2)*e^(x^2)-(1/2)*e^(x^2))|^(1)_(0)=
=(e/2)-(e/2)+1/2=1/2.