Using factorization, the missing factor is (a + 6) of the given quadratic equation a² + 8a + 12 = 0.
<h3>What is a quadratic equation?</h3>
It is a polynomial that is equal to zero. Polynomial of variable power 2, 1, and 0 terms are there. Any equation having one term in which the power of the variable is a maximum of 2 then it is called a quadratic equation.
Given
The quadratic equation is a² + 8a + 12 = 0
The factor of the quadratic equation will be.

Thus, the missing factor is (a + 6).
More about the quadratic equation link is given below.
brainly.com/question/17177510