## Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

Published by Pearson

# Chapter 5 - Polynomials and Factoring - 5.3 Factoring Trinomials of the Type ax2+bx+c - 5.3 Exercise Set - Page 326: 25

#### Answer

$(5x+4)^2$

#### Work Step by Step

Using the factoring of trinomials in the form $ax^2+bx+c,$ the $\text{ expression }$ \begin{array}{l}\require{cancel} 25x^2+40x+16 \end{array} has $ac= 25(16)=400$ and $b= 40 .$ The two numbers with a product of $c$ and a sum of $b$ are $\left\{ 20,20 \right\}.$ Using these $2$ numbers to decompose the middle term of the trinomial expression above results to \begin{array}{l}\require{cancel} 25x^2+20x+20x+16 .\end{array} Grouping the first and second terms and the third and fourth terms, the given expression is equivalent to \begin{array}{l}\require{cancel} (25x^2+20x)+(20x+16) .\end{array} Factoring the $GCF$ in each group results to \begin{array}{l}\require{cancel} 5x(5x+4)+4(5x+4) .\end{array} Factoring the $GCF= (5x+4)$ of the entire expression above results to \begin{array}{l}\require{cancel} (5x+4)(5x+4) \\\\= (5x+4)^2 .\end{array}

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