## University Calculus: Early Transcendentals (3rd Edition)

$\frac{3a^{2}}{2}$
Using equation (2), we have $\int^{2a}_{a}xdx= \frac{(2a)^{2}}{2}-\frac{a^{2}}{2}$ $=\frac{4a^{2}}{2}-\frac{a^{2}}{2}= \frac{3a^{2}}{2}$