F(x)=x^3−9x

over which interval does f have a positive average rate of change?

choose 1

(choice a)

[-4,-1]

(choice b)

[-1,2]

(choice c)

[-2,1]

(choice d)

[-3,3]

Select the correct answer from each drop-down menu. a system of equations and its solution are given below. system a complete the sentences to explain what steps were followed to obtain the system of equations below. system b to get system b, the equation in system a was replaced by the sum of that equation and times the equation. the solution to system b the same as the solution to system a.]