Example

Factoring 18w239w+1818w^2 - 39w + 18 Using the ac Method

Factor the trinomial 18w239w+1818w^2 - 39w + 18 using the ac method.

Step 1: Check for a greatest common factor (GCF). The terms 18w218w^2, 39w-39w, and 1818 share a common factor of 33. Factor it out: 18w239w+18=3(6w213w+6)18w^2 - 39w + 18 = 3(6w^2 - 13w + 6)

Step 2: Find the product acac for the trinomial inside the parentheses. Here a=6a = 6 and c=6c = 6, so ac=66=36ac = 6 \cdot 6 = 36.

Step 3: Find two numbers that multiply to 3636 and add to the middle coefficient, 13-13. These numbers are 4-4 and 9-9 (49=36-4 \cdot -9 = 36, 4+(9)=13-4 + (-9) = -13).

Step 4: Split the middle term 13w-13w into 4w9w-4w - 9w: 3(6w24w9w+6)3(6w^2 - 4w - 9w + 6)

Step 5: Factor the trinomial by grouping: 3[2w(3w2)3(3w2)]3[2w(3w - 2) - 3(3w - 2)] 3(2w3)(3w2)3(2w - 3)(3w - 2)

Step 6: Check by multiplying: 3(2w3)(3w2)=3(6w24w9w+6)=3(6w213w+6)=18w239w+183(2w - 3)(3w - 2) = 3(6w^2 - 4w - 9w + 6) = 3(6w^2 - 13w + 6) = 18w^2 - 39w + 18

The factored form is 3(2w3)(3w2)3(2w - 3)(3w - 2).

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Updated 2026-04-29

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