Step 1 :
After factoring out $ 2 $ we have:
$$ 2x^{2}+20x-70 = 2 ( x^{2}+10x-35 ) $$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:
$$ \color{blue}{ b = 10 } ~ \text{ and } ~ \color{red}{ c = -35 }$$Now we must discover two numbers that sum up to $ \color{blue}{ 10 } $ and multiply to $ \color{red}{ -35 } $.
Step 3: Find out pairs of numbers with a product of $\color{red}{ c = -35 }$.
PRODUCT = -35 | |
-1 35 | 1 -35 |
-5 7 | 5 -7 |
Step 4: Because none of these pairs will give us a sum of $ \color{blue}{ 10 }$, we conclude the polynomial cannot be factored.