Question

i am doin homework and i do not know what an interval is

Answer 1

An interval is to indicate a range of values on the number line.
For example, if we want to say:
0≤x≤10, we would say that
x is on the interval [0,10], where 0 and 10 are the limits of the interval, and [] stand for the ≥ and ≤ signs respectively.
If the limit is excluded from the interval, such as 0≤x<π
we write:
[0,π)
Same goes for
-∞<x<∞, or (-∞∞).

All this sound abstract, the best is to post a relevant question, which demonstrates the context of what you are doing in your course.

Answer 2

Enter the interval [-4,oo)