trinomial

thumb|upright=2|Layers of Pascal's pyramid derived from [[coefficients in an upside-down ternary plot of the terms in the expansions of the powers of a trinomial ]] In elementary algebra, a trinomial is a polynomial consisting of three terms or monomials.

==Examples of trinomial expressions== 3x + 5y + 8z with x, y, z variables 3t + 9s^2 + 3y^3 with t, s, y variables 3ts + 9t + 5s with t, s variables ax^2+bx+c, the quadratic polynomial in standard form with a,b,c variables. A x^a y^b z^c + B t + C s with x, y, z, t, s variables, a, b, c nonnegative integers and A, B, C any constants. Px^a + Qx^b + Rx^c where x is variable and constants a, b, c are nonnegative integers and P, Q, R any constants.