Find the measure of GTR

What is the length of an with endpoints a 3,2 and b 8,14

What is the answer to this question? i'm a bit stumped. also how do i do it? 5(x - 4) = 2(x + 5)

The position of a moving particle is given by the position function: f(t)=-9t-t^2-0.2t^3+0.1t^4 0 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)