Question

一个数学题 很简单 但是不太确定答案~急求！！！

The accompanying figure shows the velocity v(t) of a particle moving on a horizontal coordinate line, for in the closed interval [0,10] .
Answer the questions below using points, lists of points, intervals, or unions of intervals, whichever is appropriate. Note: Derivatives at the endpoint should be right-hand derivatives, while derivatives at the endpoint t=0 should be left-hand derivatives t=10.

When does the particle speed up? ANSWER:
When does the particle slow down? ANSWER:
When is the particle's acceleration positive? ANSWER:

Answer 1

加速阶段是在0-1,4-5,8-9.减速阶段是在1-2,7-8，9-10.加速度为正是在0-1,7-8,9-10

Answer 2

太深奥，看不懂，感觉不好意思。

追问

就是说根据图像 什么时候加速 什么时候减速 什么时候加速度是正

追答

不懂这外文。听了就明白一些了，谢了。