In factoring a quadratic by the ac method, which statement comes last?

• A. Identify a, b, c
• B. Set up giant X with ac in the top and b in the bottom
• C. Find factors that multiply to ac but add to b
• D. Divide factors by a and simplify

Answer: (D)

The trick in the ac method is to turn ax^2 + bx + c into a product of two binomials by using ac to guide splitting the middle term, then factoring by grouping. After finding the two numbers that multiply to ac and add to b, you rewrite and group to get something that factors nicely into binomials. The final step is to adjust those factors so they reflect the original leading coefficient a, which is done by dividing the resulting factors by a and simplifying. This normalization ensures the final factorization truly multiplies to the original quadratic and has the correct leading coefficient.