Determine the point(s) (if any) at which the graph of the function has a horizontal tangent line. ( f(x) = x^3 +15x^2 +3

Mrs. morton has a special reward system for her class. when all her students behave well, she rewards them by putting 3 marbles into a marble jar. when the jar has 100 or more marbles, the students have a party. right now, the the jar has 24 marbles. how could mrs. morton reward the class in order for the students to have a party?

Aswimming pool measures 22ft by 12ft and is 4ft deep. if the pool is being filled at 2.5 cubic ft per minute, how long will it take to fill the pool?

The function f(x)= -(x+5)(x+1) is down. what is the range of the function?