Solve these problems:

\fQuestion 15 Find the derivative y' if y=-In(cos x) . O 1/cos(x) O sin(x)/cos(x) O -cos(x)/sin(x) O -1/sin(x) O 1/sin(x) O - 1/cos(x) O -sin(x)/cos(x) O cos(x)/sin(x)\fQuestion 17 Find lim X -1 -2 X - 5 X - 5 O 4 O 12 1/6 1/12 O O 1/4 6 O 1/8Question 20 Find the linearization of f(x) =x/3 +1 at x=8. O X/12 - 1/3 O x/12 + 11/3 O x/12 + 1/3 O X/12 - 7/3 O x/12 - 11/3 O X/12 + 5/3 O X/12 + 7/3 O */12 - 5/3