Problem 3d

Step 1.

The particle is moving in the positive direction when the velocity is positive.

Therefore, we can write

                             

In , we found the solutions of as

Use these solutions to divide the number line into three intervals: 

.

Select a point from the interval to find the sign of velocity on this interval,

I am using

                       

Select a point from the interval $(2,6)$ to find the sign of velocity on this interval,

I am using

                       

Select a point from the interval to find the sign of velocity on this interval,

I am using