Example

Factoring 24x3+81y324x^3 + 81y^3

Factor 24x3+81y324x^3 + 81y^3 completely by first extracting the greatest common factor and then applying the sum of cubes pattern.

Step 1 — Check for a GCF: The two terms 24x324x^3 and 81y381y^3 share a numerical factor of 33. Factor it out: 3(8x3+27y3)3(8x^3 + 27y^3)

Step 2 — Classify the expression inside the parentheses: The expression 8x3+27y38x^3 + 27y^3 is a binomial. Both terms are perfect cubes: 8x3=(2x)38x^3 = (2x)^3 and 27y3=(3y)327y^3 = (3y)^3. Therefore, it is a sum of cubes.

Step 3 — Write it using the sum of cubes pattern: Apply the pattern a3+b3=(a+b)(a2ab+b2)a^3 + b^3 = (a + b)(a^2 - ab + b^2) with a=2xa = 2x and b=3yb = 3y: 3((2x)3+(3y)3)3((2x)^3 + (3y)^3) 3(2x+3y)((2x)2(2x)(3y)+(3y)2)3(2x + 3y)((2x)^2 - (2x)(3y) + (3y)^2)

Step 4 — Simplify and write the fully factored form: 3(2x+3y)(4x26xy+9y2)3(2x + 3y)(4x^2 - 6xy + 9y^2)

Step 5 — Check: The expression is factored completely. Verify by multiplying: 3(2x+3y)(4x26xy+9y2)=3(8x312x2y+18xy2+12x2y18xy2+27y3)=3(8x3+27y3)=24x3+81y33(2x + 3y)(4x^2 - 6xy + 9y^2) = 3(8x^3 - 12x^2y + 18xy^2 + 12x^2y - 18xy^2 + 27y^3) = 3(8x^3 + 27y^3) = 24x^3 + 81y^3 ✓.

The completely factored form is 3(2x+3y)(4x26xy+9y2)3(2x + 3y)(4x^2 - 6xy + 9y^2).

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Updated 2026-04-30

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