4.5 Factoring a Perfect Square Trinomial

A perfect square trinomial is a trinomial that can be written as the square of a binomial. Recall that when a binomial is squared, the result is the square of the first term added to twice the product of the two terms and the square of the last term.

a2+2ab+b2=(a+b)2anda22ab+b2=(ab)2 

We can use this equation to factor any perfect square trinomial.

Perfect Square Trinomials

A perfect square trinomial can be written as the square of a binomial:

a2+2ab+b2=(a+b)2

How To

Given a perfect square trinomial, factor it into the square of a binomial.

  1. Confirm that the first and last term are perfect squares.
  2. Confirm that the middle term is twice the product of [latex]ab[/latex].
  3. Write the factored form as [latex](a+b)^2[/latex].

Example 1: Factoring a Perfect Square Trinomial

  1. Factor [latex]25x^2 + 20x + 4[/latex].
  2. Factor [latex]49x^2−14x+1[/latex].

Solution

Access for free at https://openstax.org/books/algebra-and-trigonometry/pages/1-introduction-to-prerequisites

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Math 3080 Preparation Copyright © 2022 by Erin Kox is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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