Step 1 :
After factoring out $ 2 $ we have:
$$ 2x^{2}+4x-8 = 2 ( x^{2}+2x-4 ) $$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:
$$ \color{blue}{ b = 2 } ~ \text{ and } ~ \color{red}{ c = -4 }$$Now we must discover two numbers that sum up to $ \color{blue}{ 2 } $ and multiply to $ \color{red}{ -4 } $.
Step 3: Find out pairs of numbers with a product of $\color{red}{ c = -4 }$.
PRODUCT = -4 | |
-1 4 | 1 -4 |
-2 2 | 2 -2 |
Step 4: Because none of these pairs will give us a sum of $ \color{blue}{ 2 }$, we conclude the polynomial cannot be factored.