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

$(x+10)^2$
The 2 numbers whose product is $ac= 1(100)=100$ and whose sum is $b= 20$ are $\left\{ 10,10 \right\}.$ Using these two numbers to decompose the middle term of the given trinomial, $x^2+20x+100 ,$ then the factored form is \begin{array}{l} x^2+10x+10x+100 \\\\= (x^2+10x)+(10x+100) \\\\= x(x+10)+10(x+10) \\\\= (x+10)(x+10) \\\\= (x+10)^2 .\end{array}