Answer:
Polynomials are closed under addition and subtraction, which is fancy mathspeak that means that whenever we add or subtract two polynomials, we always get another polynomial. In that way, they behave a lot like the numbers you're probably already familiar with. Adding and subtracting:
- Two integers gives you another integer
- Two rational numbers gives you another rational number
- Two real numbers gives you another real number
And it works the same with polynomials!
