[] The positive interval is where the function is above the x-axis, and the negative interval is where the function is below the x-axis.
[] To find it, we can graph the function
() See attached
[] When the function is equal to less than 0, it'll be negative, otherwise it is positive
Have a nice day!
I hope this is what you are looking for, but if not - comment! I will edit and update my answer accordingly. (ノ^∇^)
- Heather