Please help with 11,13, and 14

11. Approximate the area under the graph of f(x) = 4x + 1 between r = 1 and r = 3 using a Riemann sum with n = 4 subintervals and right endpoints. 12. Evaluate the integral / | cos(I) |dx. 13. Find all of the critical points of the function f(x) = 13 - 6x -9, and classify each as a local minimum, local maximum, or neither. 14. Sketch the graph of the function f(r) = , and label the critical points and points of inflection, comain areas of increase/ decrease, cancure up/down, any jymmeity