**Definition of Trinomial**

- A trinomial is a polynomial with three terms.
- A polynomial with three terms is called a trinomial.

**Examples of Trinomial**

*x*^{2}+ 5*x*- 2, -*x*^{2}- 2*x*- 3,*x*^{2}+ 9*x*+ 6,*x*^{2}- 6*x*+ 2, -*x*^{2}- 4*x*+ 5

**Solved Example on Trinomial**

What term should be added to the expression

x^{2}+ 8x, to make it a perfect square trinomial?

Choices:

A. -16

B. 64

C. 16

D. 4

Correct Answer: C

Solution:

Step 1:x^{2}+ 8x[Original expression.]

Step 2:To complete the square of the expressionx^{2}+bx, add the square of half the coefficient ofx, that is, add .

Step 3:The coefficientb= 8, so add = = 16, to the expression.

Step 4:x^{2}+ 8x+ 4^{2}=x^{2}+ 8x+ 16 = (x+ 4)^{2}.

Step 5:16 should be added to the expression,x^{2}+ 8x, to create a perfect square trinomial.

**Related Terms for Trinomial **

- Polynomial