Problem 19. (1 point) Problem 23. (1 point) Let Let y = 13-8/x f(x) = 6In(sec(x) + tan(x)) dy f" (x) =. dx HINT: Simplify the first derivative before you find the second de- rivative. Problem 20. (1 point) Problem 24. (1 point) Let Use logarithmic differentiation to find f'(x) if y = 7+ex f(x) = (6x -2)4. (8x2 +8)4. dy f'( x ) = dx Problem 25. (1 point) Problem 21. (1 point) Find - for the function y = x-3cos(x) Let dx f(x) = -3ersinx dy dx Problem 26. (1 point) f' ( x ) = Let f (x) = xx Problem 22. (1 point) If y = 2xIn(x), find the following. Use logarithmic differentiation to determine the derivative. y= f' (x) = _ f' (1) =