Example

Factoring 6x2+7x+26x^2 + 7x + 2 Using the ac Method

Factor 6x2+7x+26x^2 + 7x + 2 by applying all six steps of the "ac" method to demonstrate how it converts a trinomial factoring problem into a factoring-by-grouping problem.

Step 1 — Factor any GCF. The terms 6x26x^2, 7x7x, and 22 share no common factor, so proceed to the next step.

Step 2 — Find the product acac. Here a=6a = 6 and c=2c = 2, so ac=62=12ac = 6 \cdot 2 = 12.

Step 3 — Find two numbers mm and nn that multiply to 12 and add to 7. Since both the product and sum are positive, both numbers must be positive. The pair m=3m = 3 and n=4n = 4 works: 34=123 \cdot 4 = 12 and 3+4=73 + 4 = 7.

Step 4 — Split the middle term 7x7x into 3x+4x3x + 4x:

6x2+7x+2=6x2+3x+4x+26x^2 + 7x + 2 = 6x^2 + 3x + 4x + 2

Step 5 — Factor by grouping. Group into two pairs and factor the GCF from each:

3x(2x+1)+2(2x+1)3x(2x + 1) + 2(2x + 1)

Both groups share the common binomial (2x+1)(2x + 1). Factor it out:

(2x+1)(3x+2)(2x + 1)(3x + 2)

Step 6 — Check by multiplying: (2x+1)(3x+2)=6x2+4x+3x+2=6x2+7x+2(2x + 1)(3x + 2) = 6x^2 + 4x + 3x + 2 = 6x^2 + 7x + 2

The factored form is (2x+1)(3x+2)(2x + 1)(3x + 2). This example shows how the numbers 3 and 4 — whose product matches ac=12ac = 12 and whose sum matches b=7b = 7 — provide exactly the right way to split the middle term so that factoring by grouping produces two binomial factors.

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Updated 2026-04-29

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