It seems that $ -x^{2}-99x+40 $ cannot be factored out.
Step 1 :
After factoring out $ -1 $ we have:
$$ -x^{2}-99x+40 = - ~ ( x^{2}+99x-40 ) $$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:
$$ \color{blue}{ b = 99 } ~ \text{ and } ~ \color{red}{ c = -40 }$$Now we must discover two numbers that sum up to $ \color{blue}{ 99 } $ and multiply to $ \color{red}{ -40 } $.
Step 3: Find out pairs of numbers with a product of $\color{red}{ c = -40 }$.
PRODUCT = -40 | |
-1 40 | 1 -40 |
-2 20 | 2 -20 |
-4 10 | 4 -10 |
-5 8 | 5 -8 |
Step 4: Because none of these pairs will give us a sum of $ \color{blue}{ 99 }$, we conclude the polynomial cannot be factored.