It is easy to show by direct computation that $\int_{a}^{\,b} {x}\, dx = \frac{b^2-a^2}{2}.$ Use this fact and the fact that $\int_{0}^{\,\pi/2} {\cos(x)}\, dx = 1,$ together with the properties of integrals, to evaluate $\int_{0}^{\,\pi/2} {(3 \cos(x) + 2 x)}\, dx\,.$