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:
$$ \color{blue}{ b = 8 } ~ \text{ and } ~ \color{red}{ c = -180 }$$Now we must discover two numbers that sum up to $ \color{blue}{ 8 } $ and multiply to $ \color{red}{ -180 } $.
Step 2: Find out pairs of numbers with a product of $\color{red}{ c = -180 }$.
PRODUCT = -180 | |
-1 180 | 1 -180 |
-2 90 | 2 -90 |
-3 60 | 3 -60 |
-4 45 | 4 -45 |
-5 36 | 5 -36 |
-6 30 | 6 -30 |
-9 20 | 9 -20 |
-10 18 | 10 -18 |
-12 15 | 12 -15 |
Step 3: Find out which pair sums up to $\color{blue}{ b = 8 }$
PRODUCT = -180 and SUM = 8 | |
-1 180 | 1 -180 |
-2 90 | 2 -90 |
-3 60 | 3 -60 |
-4 45 | 4 -45 |
-5 36 | 5 -36 |
-6 30 | 6 -30 |
-9 20 | 9 -20 |
-10 18 | 10 -18 |
-12 15 | 12 -15 |
Step 4: Put -10 and 18 into placeholders to get factored form.
$$ \begin{aligned} w^{2}+8w-180 & = (x + \color{orangered}{\square} )(x + \color{orangered}{\square}) \\ w^{2}+8w-180 & = (x -10)(x + 18) \end{aligned} $$