25%of 639 find the value :- ​

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)

Solve the following pair of equations for x and y: ax/b_ by /a= a +b; ax - by = 2ab

Rosa and lisa ade practicing free throws on the basketball court. so far,rosa has made one-and a-half times as many free throws as lisa.what is the unit ratio of rosa's free throws to lisa's free throws?