Example

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

To factor the trinomial 10y255y+7010y^2 - 55y + 70 using the 'ac' method, start by factoring out the greatest common factor (GCF). The terms 10y210y^2, 55y-55y, and 7070 share a GCF of 55. Extracting it gives 5(2y211y+14)5(2y^2 - 11y + 14). Next, apply the 'ac' method to the trinomial inside the parentheses, where a=2a = 2 and c=14c = 14. Their product is ac=214=28ac = 2 \cdot 14 = 28. Find two numbers that multiply to 2828 and add to the middle coefficient, 11-11. These numbers are 4-4 and 7-7 (since 4(7)=28-4 \cdot (-7) = 28 and 4+(7)=11-4 + (-7) = -11). Split the middle term 11y-11y into 7y4y-7y - 4y to get 5(2y27y4y+14)5(2y^2 - 7y - 4y + 14). Factor by grouping: 5[y(2y7)2(2y7)]5[y(2y - 7) - 2(2y - 7)] simplifies to 5(y2)(2y7)5(y - 2)(2y - 7). Finally, verify the factorization by multiplying the three factors together: 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 completely factored form is 5(y2)(2y7)5(y - 2)(2y - 7).

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Updated 2026-06-05

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