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

$(x-11)(x+9)$
In decreasing order of exponents, the given expression, $-2x-99+x^2 ,$ is equivalent to \begin{array}{l} x^2-2x-99 .\end{array} The 2 numbers whose product is $ac= 1(-99)=-99$ and whose sum is $b= -2$ are $\left\{ -11,9 \right\}.$ Using these two numbers to decompose the middle term of the above trinomial, then \begin{array}{l} x^2-11x+9x-99 \\\\= (x^2-11x)+(9x-99) \\\\= x(x-11)+9(x-11) \\\\= (x-11)(x+9) .\end{array}