F(x)= - 4Sin(x)Cos (x) on (-Ï, Ï) Required:

a. Find the critical numbers of f.

b. Determine the intervals on which is increasing and decreasing.

Sanderson is having trouble with his assignment. his shown work is as follows: − 3 7 7 3 = − 3 7 × 7 3 = − 21 21 = −1 however, his answer does not match the answer that his teacher gives him. complete the description of sanderson's mistake. find the correct answer.