20. State the integral that represents the area bounded byf (x) = Vx, the x-axis, between x = 0 and x = 9. Find the area by evaluating the integral. (Sketch before you integrate!) 21. Show S /2 a cos (x) dx = a (hint: start by showing So "/2 cos (x) dx = 1) 13. Graph indicating intervals of increasing and decreasing . Intervals of concave up and down . Critical values . State the 2nd Derivative Test and use it to identify the relative extrema . Domain, range. State all tests used. f(x) = x3 -3x2+3