Question 241500
Hello, 
This is quite a loaded question since many many pages can be written about trinomials. 
To begin, the word means: tri- (which is 3) and -nomial (is name or term). So it's 3 names or terms. 
Here's an example of a trinomial  3x^2 + 2x + 17  this can also be called a polynomial. (Poly means several)
RJ Toftness
www.math-unlock.com