How to find the volume of a complex solid

1mile equals approximately 1.6 kilometers. which best approximates the number of miles in 6 kilometers?

What are the solutions of the equation? 6x^2 + 11x + 4 = 0 a. 4/3, 1/2 b. -4/3, -1/2 c. 4/3, -1/2 d. -4/3, 1/2

The position of a moving particle is given by the position function: f(t)=-9t-t^2-0.2t^3+0.1t^4 a. at what time does the particle reverse direction? b. when is the displacement positive? (round one decimal place and answer in interval notation) c. when is the displacement negative? (round one decimal place and answer in interval notation) d. when is the particle’s acceleration positive? (round one decimal place and answer in interval notation) e. when is the particle’s acceleration negative? (round one decimal place and answer in interval notation)