Example

Factoring x2+12xy+36y2x^2 + 12xy + 36y^2

Factor x2+12xy+36y2x^2 + 12xy + 36y^2 by applying the two-variable trinomial factoring strategy. Because the first term is x2x^2, each binomial factor begins with xx. Because the last term contains y2y^2, the second term of each binomial must include yy.

Step 1 — Set up two binomials: (x_y)(x_y)(x\_y)(x\_y), where each blank will be filled with a coefficient of yy.

Step 2 — Find two numbers that multiply to 36 and add to 12. List the factor pairs of 36 and check their sums:

Factors of 36Sum of factors
1,361, 361+36=371 + 36 = 37
2,182, 182+18=202 + 18 = 20
3,123, 123+12=153 + 12 = 15
4,94, 94+9=134 + 9 = 13
6,66, 66+6=126 + 6 = 12

The pair 6 and 6 has a product of 36 and a sum of 12.

Step 3 — Use 6 and 6 as the coefficients of yy in the last terms: (x+6y)(x+6y)(x + 6y)(x + 6y).

Step 4 — Check by multiplying: (x+6y)(x+6y)=x2+6xy+6xy+36y2=x2+12xy+36y2(x + 6y)(x + 6y) = x^2 + 6xy + 6xy + 36y^2 = x^2 + 12xy + 36y^2 ✓.

The factored form is (x+6y)(x+6y)(x + 6y)(x + 6y). This example illustrates that when both factor-pair numbers are equal, the two binomials are identical, making the trinomial a perfect square in two variables.

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Updated 2026-04-21

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