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:
$$ \color{blue}{ b = -19 } ~ \text{ and } ~ \color{red}{ c = -150 }$$Now we must discover two numbers that sum up to $ \color{blue}{ -19 } $ and multiply to $ \color{red}{ -150 } $.
Step 2: Find out pairs of numbers with a product of $\color{red}{ c = -150 }$.
PRODUCT = -150 | |
-1 150 | 1 -150 |
-2 75 | 2 -75 |
-3 50 | 3 -50 |
-5 30 | 5 -30 |
-6 25 | 6 -25 |
-10 15 | 10 -15 |
Step 3: Find out which pair sums up to $\color{blue}{ b = -19 }$
PRODUCT = -150 and SUM = -19 | |
-1 150 | 1 -150 |
-2 75 | 2 -75 |
-3 50 | 3 -50 |
-5 30 | 5 -30 |
-6 25 | 6 -25 |
-10 15 | 10 -15 |
Step 4: Put 6 and -25 into placeholders to get factored form.
$$ \begin{aligned} y^{2}-19y-150 & = (x + \color{orangered}{\square} )(x + \color{orangered}{\square}) \\ y^{2}-19y-150 & = (x + 6)(x -25) \end{aligned} $$