Given the equation:

Let's use factoring form to change the equation from standard form to factored form.
Let's factor using the AC method.
Find a pair of numbers whose sum is -10 and whose product is 21.
We have the pair:
-3 and -7
Proof:
-3 + (-7) = -10
-3 x (-7) = 21
Now, we have the factored form using the pair of numbers:

Therefore, the factored form is:

ANSWER:
