Madelyn simplified the expression 3(4y) + 6 + 2y using the following steps:
3(4y) + 6 + 2y
v
12y + 6 + 2y
v
12y + 2y + 6
v
14y + 6
which property did she use in simplifying?
-commutative property of multiplication
-commutative property of addition
-associative property of multiplication
-associative property of addition

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)