Suppose you know that integral (0 to 3) f(x) dx = 6 , what is the integral (0 to 3)(f(x) + 5x)?

We can break down down into the sum of integrals

integral (0 to 3)f(x) dx + integral (0 to 3) 5x dx

= 6 + [(5/2)x^2) evaluated at 3... = 6 + (5/2)(9) = 6 + 45/2 = 28.5