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:
$$ \color{blue}{ b = -1 } ~ \text{ and } ~ \color{red}{ c = -132 }$$Now we must discover two numbers that sum up to $ \color{blue}{ -1 } $ and multiply to $ \color{red}{ -132 } $.
Step 2: Find out pairs of numbers with a product of $\color{red}{ c = -132 }$.
PRODUCT = -132 | |
-1 132 | 1 -132 |
-2 66 | 2 -66 |
-3 44 | 3 -44 |
-4 33 | 4 -33 |
-6 22 | 6 -22 |
-11 12 | 11 -12 |
Step 3: Find out which pair sums up to $\color{blue}{ b = -1 }$
PRODUCT = -132 and SUM = -1 | |
-1 132 | 1 -132 |
-2 66 | 2 -66 |
-3 44 | 3 -44 |
-4 33 | 4 -33 |
-6 22 | 6 -22 |
-11 12 | 11 -12 |
Step 4: Put 11 and -12 into placeholders to get factored form.
$$ \begin{aligned} x^{2}-x-132 & = (x + \color{orangered}{\square} )(x + \color{orangered}{\square}) \\ x^{2}-x-132 & = (x + 11)(x -12) \end{aligned} $$