(Revision 15) (4 points) 9. Let f(x)=3x" +x -2 a. Find an interval where the function /" has one root. b. Use Rolle's theorem to show that the function / has exactly one root. Hint. See Example 2 on page 283 of the textbook. (4 points) 10. Use the identity cos x + sin\" x = | to integrate Icos3x sin\" x dx. (12 points) 1 1. Evaluate each of the definite integrals listed below a. [ cost (3x) dx b. sin(2x) sin x dx c. [x2 + cos(2x) dx (6 points) 12. Apply the fundamental theorem of calculus to find the following derivative- dx tan (3t) dt. -x