Hello!
The answer is:
The polynomial have 3 terms. (it's a trinomial).
Why?
A polynomial is an expression which consists of one or more terms (numbers or variables) being added or subtracted.
So, we are given the polynomial:
[tex]x^{2} +xy-y^{2}[/tex]
We have that there are three terms separated by differents being added and subtracted, so, the polynomial has 3 terms, and it's a trinomial.
Have a nice day!
