Aloha :)
$$\left(u(x)\cdot v(x)\right)'=u'(x)\cdot v(x)+u(x)\cdot v'(x)\quad\implies$$$$\int\limits_a^b\left(u(x)\cdot v(x)\right)'\,dx=\int\limits_a^bu'(x)\cdot v(x)\,dx+\int\limits_a^bu(x)\cdot v'(x)\,dx\quad\implies$$$$\left[u(x)\cdot v(x)\right]_a^b=\int\limits_a^bu'(x)\cdot v(x)\,dx+\int\limits_a^bu(x)\cdot v'(x)\,dx\quad\implies$$$$u(b)\cdot v(b)-u(a)\cdot v(a)=\int\limits_a^bu'(x)\cdot v(x)\,dx+\int\limits_a^bu(x)\cdot v'(x)\,dx\quad\implies$$$$\int\limits_a^bu(x)\cdot v'(x)\,dx=u(b)\cdot v(b)-u(a)\cdot v(a)-\int\limits_a^bu'(x)\cdot v(x)\,dx$$