Example

Factoring 10y255y+7010y^2 - 55y + 70 Using the ac Method

Factor the trinomial 10y255y+7010y^2 - 55y + 70 using the ac method.

Step 1: Check for a greatest common factor (GCF). The terms 10y210y^2, 55y-55y, and 7070 share a common factor of 55. Factor it out: 10y255y+70=5(2y211y+14)10y^2 - 55y + 70 = 5(2y^2 - 11y + 14) The trinomial inside the parentheses has a leading coefficient that is not 11.

Step 2: Find the product acac. Here a=2a = 2 and c=14c = 14, so ac=214=28ac = 2 \cdot 14 = 28.

Step 3: Find two numbers that multiply to 2828 and add to the middle coefficient, 11-11. These numbers are 4-4 and 7-7 (47=28-4 \cdot -7 = 28, 4+(7)=11-4 + (-7) = -11).

Step 4: Split the middle term 11y-11y into 7y4y-7y - 4y: 5(2y27y4y+14)5(2y^2 - 7y - 4y + 14)

Step 5: Factor the trinomial by grouping: 5[y(2y7)2(2y7)]5[y(2y - 7) - 2(2y - 7)] 5(y2)(2y7)5(y - 2)(2y - 7)

Step 6: Check by multiplying all three factors: 5(y2)(2y7)=5(2y27y4y+14)=5(2y211y+14)=10y255y+705(y - 2)(2y - 7) = 5(2y^2 - 7y - 4y + 14) = 5(2y^2 - 11y + 14) = 10y^2 - 55y + 70

The factored form is 5(y2)(2y7)5(y - 2)(2y - 7).

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Updated 2026-04-29

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