1. Calculate the following limits. (12) a. lim ac2 + 2 x + 1 x--1 2 2 - 1 b. 204 - 20 - 6 lim x--1 x2 + 5x + 4 C. lim c-+0 d. lim sin x x-0 x2 + 4x 2. For each of the following functions, find a value of a that makes the function continuous or demonstrate that no value of a is possible. (12) a. f (x) _ sin(x + a x> T cos x b. a