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

$(b-7)^2$
Using the factoring of trinomials in the form $x^2+bx+c,$ the $\text{ expression }$ \begin{array}{l}\require{cancel} b^2-14b+49 \end{array} has $c= 49$ and $b= -14 .$ The two numbers with a product of $c$ and a sum of $b$ are $\left\{ -7,-7 \right\}.$ Using these two numbers, the $\text{ expression }$ above is equivalent to \begin{array}{l}\require{cancel} (b-7)(b-7) \\\\= (b-7)^2 .\end{array}