Factoring Trinomials Calculator

Factor quadratic trinomials ax² + bx + c into integer binomial products.

Factor a quadratic trinomial
Enter integer coefficients for ax² + bx + c. The leading coefficient cannot be zero.

About factoring trinomials

Factoring a quadratic trinomial reverses polynomial multiplication. An expression in the form ax² + bx + c is rewritten as a product of two linear binomials when integer factors exist. For example, x² + 5x + 6 becomes (x + 2)(x + 3). Expanding the result gives x² + 3x + 2x + 6, which combines back to the original expression. For a monic trinomial, where a equals 1, look for two integers whose product is c and whose sum is b. Those integers become the constants in the two factors. Signs matter: x² - 5x + 6 requires two negative constants, producing (x - 2)(x - 3), because their product is positive 6 and their sum is negative 5. When the leading coefficient is not 1, the AC method provides a systematic path. Multiply a by c, find two integers whose product is ac and whose sum is b, split the middle term with those values, and factor by grouping. For 2x² + 7x + 3, the product ac is 6 and the useful pair is 6 and 1. Grouping 2x² + 6x + x + 3 produces (x + 3)(2x + 1). The discriminant b² - 4ac quickly indicates whether rational linear factors are possible. If it is negative, the quadratic has no real roots and cannot factor into real linear terms. If it is nonnegative but not a perfect square for integer coefficients, the roots are irrational and no integer binomial factorization exists. The calculator reports such expressions as not factorable over the integers rather than forcing an incorrect product. Special patterns can make factoring faster. A difference of squares such as x² - 9 factors as (x - 3)(x + 3). A perfect-square trinomial such as x² + 6x + 9 factors as (x + 3)(x + 3). If all coefficients share a greatest common factor, remove that content first and place it before the binomial product. Factored form reveals the zeros of a quadratic equation. If a product of two factors equals zero, each factor can be set equal to zero to find the roots. This is useful for graph intercepts, projectile-time equations, area models, and algebraic simplification. Always verify a factorization by multiplying the binomials and confirming that the x², x, and constant coefficients match the original trinomial exactly.

Factoring trinomial examples

These examples cover monic, nonmonic, special-pattern, and unfactorable cases.

TrinomialFactored formMethod
x² + 5x + 6(x + 2)(x + 3)Two numbers multiply to 6 and add to 5.
2x² + 7x + 3(x + 3)(2x + 1)Use the AC method and grouping.
x² - 9(x - 3)(x + 3)Difference of squares.
x² + x + 1Not factorable over the integersThe discriminant is negative.

How to factor a trinomial

  1. Enter the integer coefficient of x² in the a field, using 1 when no coefficient is written.
  2. Enter the signed coefficient of x in the b field, using 0 when the term is absent.
  3. Enter the signed constant in the c field.
  4. Select Factor Trinomial to search for integer binomial factors.
  5. Expand the displayed product mentally or on paper to verify the result.

Factoring trinomials FAQ

What does factorable over the integers mean?

It means the polynomial can be written as a product whose coefficients are integers. Some quadratics have irrational or complex roots and therefore do not have integer binomial factors.

How does the discriminant help with factoring?

For integer coefficients, a nonnegative perfect-square discriminant indicates rational roots and an integer factorization after content is removed. A negative or nonsquare discriminant rules out that form.

What if coefficient a is zero?

Then the expression is linear rather than quadratic, so it is not a trinomial in the required form. This calculator requires a nonzero leading coefficient.

Can the calculator factor a difference of squares?

Yes, enter zero for the middle coefficient. For example, coefficients 1, 0, and -9 produce (x - 3)(x + 3).

How can I check the answer?

Multiply the two binomials using distribution or FOIL and combine like terms. The resulting three coefficients should exactly match a, b, and c.