Answer
$\int_1^{20}udv=101$
Work Step by Step
Using integration by parts,
$\int vdu =uv -\int u dv$
Therefore,
$\int _1^{20}vdu =uv|_1^{20} -\int_1^{20}u dv=-1$
$\implies\int_1^{20} udv=uv|_1^{20} +1$
$\implies\int_1^{20}u dv = (15\times6)-(5\times (-2))+1=101$
