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