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:
$$ \color{blue}{ b = 30 } ~ \text{ and } ~ \color{red}{ c = 200 }$$Now we must discover two numbers that sum up to $ \color{blue}{ 30 } $ and multiply to $ \color{red}{ 200 } $.
Step 2: Find out pairs of numbers with a product of $\color{red}{ c = 200 }$.
PRODUCT = 200 | |
1 200 | -1 -200 |
2 100 | -2 -100 |
4 50 | -4 -50 |
5 40 | -5 -40 |
8 25 | -8 -25 |
10 20 | -10 -20 |
Step 3: Find out which pair sums up to $\color{blue}{ b = 30 }$
PRODUCT = 200 and SUM = 30 | |
1 200 | -1 -200 |
2 100 | -2 -100 |
4 50 | -4 -50 |
5 40 | -5 -40 |
8 25 | -8 -25 |
10 20 | -10 -20 |
Step 4: Put 10 and 20 into placeholders to get factored form.
$$ \begin{aligned} x^{2}+30x+200 & = (x + \color{orangered}{\square} )(x + \color{orangered}{\square}) \\ x^{2}+30x+200 & = (x + 10)(x + 20) \end{aligned} $$