Please Help A particle moves according to a law of motion s = f(t) = t3 - 12t2 + 45t, t 0, where t is measured in seconds and s in feet.
a. When is the particle speeding up?
(,)U(,)

b. When is it slowing down?
(,)U(,)

Simonne used the following steps to simplify the given expression. 12-3(-2x+4) step 1: 12+(-)+(-3)(4) step 2: 12+6x+(-12) step 3: 12+(-12)+6x step 4: 0+6x step 5: 6x what property of real numbers was used to transition from step 3 to step 4? •identity property of addition •inverse property of addition •associative property of addition •commutative property of addition