2. Вычислить интеграл: а) ∫(9/√x)dx; б) ∫(π/4) cosxdx

a) \int_{1}^{9} \frac{1}{\sqrt{x}}dx = [2\sqrt{x}]_{1}^{9} = 2\sqrt{9} - 2\sqrt{1} = 6 - 2 = 4
б) \int_{0}^{\pi/4} cosxdx = [sinx]_{0}^{\pi/4} = sin(\pi/4) - sin(0) = \frac{\sqrt{2}}{2}