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:

$$ \color{blue}{ b = -1 } ~ \text{ and } ~ \color{red}{ c = -992 }$$

Now we must discover two numbers that sum up to $ \color{blue}{ -1 } $ and multiply to $ \color{red}{ -992 } $.

Step 2: Find out pairs of numbers with a product of $\color{red}{ c = -992 }$.

PRODUCT = -992
-1     992	1     -992
-2     496	2     -496
-4     248	4     -248
-8     124	8     -124
-16     62	16     -62
-31     32	31     -32

Step 3: Find out which pair sums up to $\color{blue}{ b = -1 }$

PRODUCT = -992 and SUM = -1
-1     992	1     -992
-2     496	2     -496
-4     248	4     -248
-8     124	8     -124
-16     62	16     -62
-31     32	31     -32

Step 4: Put 31 and -32 into placeholders to get factored form.

$$ \begin{aligned} a^{2}-a-992 & = (x + \color{orangered}{\square} )(x + \color{orangered}{\square}) \\ a^{2}-a-992 & = (x + 31)(x -32) \end{aligned} $$

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