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:
$$ \color{blue}{ b = -10 } ~ \text{ and } ~ \color{red}{ c = 16 }$$Now we must discover two numbers that sum up to $ \color{blue}{ -10 } $ 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: Find out which pair sums up to $\color{blue}{ b = -10 }$
PRODUCT = 16 and SUM = -10 | |
1 16 | -1 -16 |
2 8 | -2 -8 |
4 4 | -4 -4 |
Step 4: Put -2 and -8 into placeholders to get factored form.
$$ \begin{aligned} x^{2}-10x+16 & = (x + \color{orangered}{\square} )(x + \color{orangered}{\square}) \\ x^{2}-10x+16 & = (x -2)(x -8) \end{aligned} $$