Step 1 :
After factoring out $ 8n^{2} $ we have:
$$ 8n^{4}+88n^{3}-1216n^{2} = 8n^{2} ( n^{2}+11n-152 ) $$Step 2 :
Step 2: 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:
$$ \color{blue}{ b = 11 } ~ \text{ and } ~ \color{red}{ c = -152 }$$Now we must discover two numbers that sum up to $ \color{blue}{ 11 } $ and multiply to $ \color{red}{ -152 } $.
Step 3: Find out pairs of numbers with a product of $\color{red}{ c = -152 }$.
PRODUCT = -152 | |
-1 152 | 1 -152 |
-2 76 | 2 -76 |
-4 38 | 4 -38 |
-8 19 | 8 -19 |
Step 4: Find out which pair sums up to $\color{blue}{ b = 11 }$
PRODUCT = -152 and SUM = 11 | |
-1 152 | 1 -152 |
-2 76 | 2 -76 |
-4 38 | 4 -38 |
-8 19 | 8 -19 |
Step 5: Put -8 and 19 into placeholders to get factored form.
$$ \begin{aligned} n^{2}+11n-152 & = (x + \color{orangered}{\square} )(x + \color{orangered}{\square}) \\ n^{2}+11n-152 & = (x -8)(x + 19) \end{aligned} $$