Answer
$(b-7)^2$
Work Step by Step
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}
