Вычислите интеграл: а) ∫[1,3] 6x²dx; б) ∫[π/4, π/2] 4cos2xdx.

а) ∫[1,3] 6x²dx = [2x³] |[1,3] = 2(3)³ - 2(1)³ = 54 - 2 = 52.

б) ∫[π/4, π/2] 4cos2xdx = [2sin2x] |[π/4, π/2] = 2sin(π) - 2sin(π/2) = 2(0) - 2(1) = -2.