It seems that $ x^{2}-2x-16 $ cannot be factored out.
Step 1: Identify constants $ \color{blue}{ b }$ and $\color{red}{ c }$. ( $ \color{blue}{ b }$ is a number in front of the $ x $ term and $ \color{red}{ c } $ is a constant). In our case:
$$ \color{blue}{ b = -2 } ~ \text{ and } ~ \color{red}{ c = -16 }$$Now we must discover two numbers that sum up to $ \color{blue}{ -2 } $ and multiply to $ \color{red}{ -16 } $.
Step 2: Find out pairs of numbers with a product of $\color{red}{ c = -16 }$.
PRODUCT = -16 | |
-1 16 | 1 -16 |
-2 8 | 2 -8 |
-4 4 | 4 -4 |
Step 3: Because none of these pairs will give us a sum of $ \color{blue}{ -2 }$, we conclude the polynomial cannot be factored.