Given that (a + b, a), (a - b, 2a) and (b, c) are collinear points, express c in terms of a and b.

What is the number 321,000,000 in scientific notation? also what is the number? ?

What is the correlation coefficient between the variables? round to three decimal places. enter your answer in the box

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)