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:
$$ \color{blue}{ b = 13 } ~ \text{ and } ~ \color{red}{ c = 36 }$$Now we must discover two numbers that sum up to $ \color{blue}{ 13 } $ and multiply to $ \color{red}{ 36 } $.
Step 2: Find out pairs of numbers with a product of $\color{red}{ c = 36 }$.
PRODUCT = 36 | |
1 36 | -1 -36 |
2 18 | -2 -18 |
3 12 | -3 -12 |
4 9 | -4 -9 |
6 6 | -6 -6 |
Step 3: Find out which pair sums up to $\color{blue}{ b = 13 }$
PRODUCT = 36 and SUM = 13 | |
1 36 | -1 -36 |
2 18 | -2 -18 |
3 12 | -3 -12 |
4 9 | -4 -9 |
6 6 | -6 -6 |
Step 4: Put 4 and 9 into placeholders to get factored form.
$$ \begin{aligned} w^{2}+13w+36 & = (x + \color{orangered}{\square} )(x + \color{orangered}{\square}) \\ w^{2}+13w+36 & = (x + 4)(x + 9) \end{aligned} $$