How to find where the tangent line is horizontal?

What is coefficient of the term of degree of degree 5 in the polynomial below

Determine the common ratio and find the next three terms of the geometric sequence. 10, 2, 0.4, a. 0.2; -0.4, -2, -10 c. 0.02; 0.08, 0.016, 0.0032 b. 0.02; -0.4, -2, -10 d. 0.2; 0.08, 0.016, 0.0032 select the best answer from the choices provided a b c d

700 miles the train takes 5 hours to a travel the distance at what unit rate is the train traveling?