Example

Factoring y211y+28y^2 - 11y + 28

To factor the trinomial y211y+28y^2 - 11y + 28, apply the strategy for trinomials of the form x2+bx+cx^2 + bx + c.

Step 1 — Set up two binomials with first terms yy: (y)(y)(y\quad)(y\quad).

Step 2 — Find two numbers that multiply to 2828 and add to 11-11. Because the constant term (2828) is positive and the middle term (11y-11y) is negative, both numerical factors must be negative.

List the negative factor pairs of 2828 and check their sums:

  • 1-1 and 28-28: sum is 29-29
  • 2-2 and 14-14: sum is 16-16
  • 4-4 and 7-7: sum is 11-11

The pair 4-4 and 7-7 works because their product is 2828 and their sum is 11-11.

Step 3 — Use 4-4 and 7-7 as the last terms of the binomials: (y4)(y7)(y - 4)(y - 7).

Step 4 — Check by multiplying: (y4)(y7)=y27y4y+28=y211y+28(y - 4)(y - 7) = y^2 - 7y - 4y + 28 = y^2 - 11y + 28.

The factored form is (y4)(y7)(y - 4)(y - 7).

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Updated 2026-04-29

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