Multiplying Binomials

Multiply two binomials (ax+b)(cx+d) and get the expanded polynomial with x^2 coefficient, x coefficient, and constant term displayed instantly for free.

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About This Calculator

The Multiplying Binomials calculator computes the product of two linear binomial expressions in the form (ax + b)(cx + d) and returns the expanded quadratic polynomial along with each individual coefficient. The multiplication follows the distributive property, also known as the FOIL method (First, Outer, Inner, Last): multiply the first terms (a x c) to get the x^2 coefficient, the outer terms (a x d) and inner terms (b x c) and add them for the x coefficient, and multiply the last terms (b x d) for the constant term. The result is displayed as a fully expanded quadratic: acx^2 + (ad + bc)x + bd.

This tool is ideal for algebra students learning polynomial multiplication, teachers preparing classroom examples, tutors demonstrating the distributive property, and anyone who needs quick binomial expansion results for homework, test preparation, or self-study. It handles any real-number coefficients including integers, fractions (decimals), and negative values, making it suitable for problems ranging from basic algebra to advanced coursework. Unlike the FOIL calculator which shows each multiplication step individually, this calculator focuses on delivering the final expanded result and coefficient breakdown instantly.

Examples: (x + 2)(x + 3) = x^2 + 5x + 6 (x^2 coefficient: 1, x coefficient: 5, constant: 6). (2x - 1)(x + 4) = 2x^2 + 7x - 4 (x^2 coefficient: 2, x coefficient: 7, constant: -4). (3x + 2)(-x + 5) = -3x^2 + 13x + 10 (x^2 coefficient: -3, x coefficient: 13, constant: 10). (-x + 1)(x - 1) = -x^2 + 2x - 1 (x^2 coefficient: -1, x coefficient: 2, constant: -1).

How to use: Enter the four coefficients from your two binomials (ax + b)(cx + d) -- a and b from the first binomial, c and d from the second. Click Calculate and the expanded polynomial, x^2 coefficient, x coefficient, and constant term appear instantly. Use the Share button to copy a link with your current inputs for later reference or to share with classmates.

Frequently Asked Questions

What is the formula for multiplying binomials?

The product (ax+b)(cx+d) expands to acx^2 + (ad+bc)x + bd. Multiply the first terms (axc), outer terms (axd), inner terms (bxc), and last terms (bxd), then combine like terms for the x coefficient.

How is multiplying binomials different from FOIL?

They are the same operation. FOIL (First, Outer, Inner, Last) is a mnemonic for the four multiplication steps when multiplying two binomials. This calculator focuses on the multiplication result, while the dedicated FOIL calculator shows each step separately.

Can I multiply binomials with three or more terms?

No, this calculator is designed for binomials (two-term expressions). For polynomials with more terms, use the Multiplying Polynomials calculator which supports higher-degree polynomials.

What types of coefficients are supported?

The calculator supports integers, fractions (decimals), and negative numbers. For example, (0.5x - 2)(-3x + 1.5) works correctly and produces the expanded form.

Is this binomial multiplication tool free?

Yes, all calculators on Calculy are completely free to use with no registration or hidden charges.

Can I share my calculation results?

Yes, use the Share button to copy the URL with your current inputs. Anyone opening that link will automatically see the same binomials and results.

What is the difference between this and the Box Method calculator?

The Box Method calculator shows the multiplication using a 2x2 area model grid, visually organizing the four partial products. This Multiplying Binomials calculator directly shows the final expanded polynomial and its coefficients without the grid visualization. Both calculators produce identical results using the same underlying formula.

Can this calculator handle squared binomials like (x+5)^2?

Yes. Enter the binomial twice -- set a and b for (x+5) and c and d for (x+5) as well. For (x+5)^2, enter a=1, b=5, c=1, d=5 to get x^2 + 10x + 25. The calculator treats any two binomials identically, so repeating the same binomial produces the perfect square expansion.