11. Let g(x) = f(2x). Show that the average value of f on the interval [0, 2b] is the same as the average value of g on the interval [0, b]. 1 12. - (8:x + 12)2 13. - 2 sin"(x) cos(x) dr 14. evx2 - 3 dr 15. 5t sin (15) dt : 16. (x1 + 7) 17. V4r + 5 de 18. sin (2t) dt -1.5 19. 10(2x - 3)1 de -0.5