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Last updated on September 29, 2025

Multiplying Binomials

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An algebraic expression that has two terms and is connected with a plus or a minus sign is known as a binomial. Multiplying binomials follows the same basic rules as multiplying numbers, but accounting for variables and like terms. We can multiply binomials using different methods. In this article, we will learn more about binomials, how to multiply them, and the methods of multiplying binomials.

Multiplying Binomials for US Students
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What are Binomials?

The algebraic expressions are classified into different types based on the numbers of terms, such as monomials, binomials, trinomials, and polynomials. Polynomials with exactly two terms, and combined by addition or subtraction, are called binomials. 2x + 3 and x2 + 2 are some examples of binomials.

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How to Multiply Binomials?

Multiplying binomials is similar to multiplying numbers, but it involves variables instead of numbers. The key difference is that binomials involve multiplying algebraic expressions, requiring attention to variables and like terms. 

 

To multiply binomials, first multiply each term in the first binomial by each term in the second binomial and then combine the like terms using addition or subtraction. The methods of multiplying binomials are:

 

  • Distributive Property

 

  • FOIL Method

 

  • Vertical Method
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Distributive Property

The distributive property involves multiplying each term inside the parentheses by the terms outside, and then combining the results. We can see how to multiply a binomial using the distributive property by the following steps:

Multiply (x + 2)(x + 3)

 

In distributive property, we need to multiply the first term of the first binomial with all the terms in the second binomial, and then the second term from the first binomial with all the terms in the second binomial.

 

Multiply x by (x + 3) = x2 + 3x

Multiply 2 by (x + 3) = 2x + 6

Add both, the result: x2 + 3x + 2x + 6 

Add the like terms: x2 + 5x + 6

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FOIL Method

FOIL method is used to multiply the binomials. The word FOIL stands for First, Outer, Inner, and Last, it refers to the order in which the terms should be multiplied. 

 

Example: Multiply: (x + 2)(x + 3)

First: Multiply the first terms of both binomials. 

x × x = x2

 

Outer: Then multiply the first term of the first binomial by the second term of the second binomial.

x × 3 = 3x

 

Inner: Multiply the inner terms from the binomials, i.e., second term from the first binomial with first term in the second binomial. 

2 × x = 2x

 

Last: Multiply the last terms of binomials.

2 × 3 = 6

 

Combine the terms by adding the like terms.

x2 + 3x + 2x + 6 = x2 + 5x + 6

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Vertical Method

To multiply the binomials using the vertical method, we can use the following steps with the example, (x + 2)(x + 3).

Arrange the binomials one below the other.


Multiply each term:
x × x = x2
x × 3 = 3x
2 × x = 2x
2 × 3 = 6

Line up terms and add the like terms.

So the final answer is: x2 + 5x + 6 

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Real Life Applications of Multiplying Binomials

Multiplying binomials is not only used in math, it helps to solve many problems in real-life situations. When we multiply binomials, we are finding areas, calculating profits, or solving physics problems. Listed below are some real-life applications of multiplying polynomials.

 

  • Construction: Multiplying binomials is used to calculate the area of rectangular space. For example, if the length of the floor is (x + 2) meters and the width is (x + 3) meters, the area of the room will be their product, it can be used to estimate the materials required. 

 

  • Business and Finance: In business and finance, multiplying binomials helps in pricing, budgeting, and maximizing profit.

 

  • Data Analysis and Statistics: In statistics, binomials are used to create models and to make predictions. For example, a business might predict sales by using the binomials to estimate growth and change. 

 

  • Game Designing: Developers use polynomial expressions like binomials to model movement of characters, calculate distances, or create animations. Multiplying expressions helps to simulate how fast something moves.
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Common Mistakes and How to Avoid Them in Multiplying Binomial

Multiplying binomials is easy, but errors in signs or term order can lead to mistakes. Here are some of the mistakes and the ways to avoid them.

Mistake 1

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Not multiplying all the terms

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Students sometimes only multiply a part of the binomials, and it results in errors.

 

For example, when multiplying (x + 2)(x + 3) students only multiply the x terms together and avoid other terms, and it is wrong. To avoid this error, always multiply each term in the first binomial by each term in the second binomial.

Mistake 2

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Sign error in multiplication

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When multiplying binomials one common error students make is incorrectly multiplying signs and it leads to mistakes.

 

For example, students assume (x -4)(x + 2) = x2 + 8x - 8 instead of x2 - 2x - 8. So when working with binomials with negative signs, always remember the sign rules: that the product of the same sign is positive and the opposite sign is negative.

Mistake 3

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Mixing up FOIL steps

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Students sometimes only use the first and last and ignore the outer and inner terms.

 

For example, students consider (x +1)(x + 5) = x2 + 5 instead of x2 + 6x + 5. When applying the FOIL method, it is important to follow the order that is first, outer, inner, and last. 

Mistake 4

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Not combining the like terms

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Students sometimes forget to add the like terms, and it can lead to errors. So students should always double check whether they add the like terms or not.

Mistake 5

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Multiplying binomials like addition

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Multiplying binomials means expanding and simplifying, not just adding the terms. Students might think it is like normal addition and add the terms of the binomials.

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Solved Examples of Multiplying Binomial

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Problem 1

Multiply: (x + 4)(x + 2)

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x2 + 6x + 8

Explanation

We can use the FOIL method for multiplying the given polynomials.

First: x × x = x2

Outer: x × 2 = 2x

Inner: 4 × x = 4x

Last: 4 × 2 = 6

 

Combine the like terms: 

X2 + 2x + 4x + 8 = x2 + 6x + 8

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Problem 2

Multiply: (x + 2)(x + 5)

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x2 + 7x + 10

Explanation

Use the distributive property.

 

Multiply the x from the first binomial to both terms in the second bracket,

x × x = x2

x × 5 = 5x

 

Multiply the 2 in the first binomial to all the terms in the second binomial,

2 × x = 2x

2 × 5 = 10

 

Combine the terms:

x2 + 5x + 2x + 10 = x2 + 7x + 10

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Problem 3

Multiply: (x - 4)(x + 3)

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x2 - x - 12

Explanation

Using the FOIL method.

First: x × x = x2

Outer: x × 3 = 3x

Inner: -4 × x = -4x

Last: -4 × 3 = -12

 

Combine the like terms:

X2 + 3x - 4x - 12 = x2 - x - 12

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Problem 4

Multiply (2x + 1)(x + 4)

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2x2 + 9x + 4

Explanation

Distribute 2x and 1 across the second binomial.

2x × x = 2x2

2x × 4 = 8x

1 × x = x

1 × 4 = 4

 

Add the terms: 2x2 + 8x + x + 4 = 2x2 + 9x + 4

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Problem 5

Multiply: (x - 5)(x - 2)

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x2 - 7x + 10

Explanation

To multiply (x - 5)(x - 2), we apply the FOIL method:

 

(a + b)(c + d) = ac + ad + bc + bd

Here, a = x, b = (-5), c = x, and d = (-2)

(x - 5)(x -2) = (x × x) + (x × -2) + (-5 × x) + (-5 × -2)

= x2 + (-2x) + (-5x) + 10

= x2 - 7x + 10

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FAQs of Multiplying Binomial

1.What is a binomial?

The algebraic expression with two terms is a binomial and is connected using addition or subtraction.

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2.Why do we multiply binomials?

Binomials are multiplied to find the areas, solving equations, or simplifying the expressions.

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3.What are the different methods to multiply binomials?

There are three common methods for multiplying binomials. They are:

 

  • Distributive Property
     
  • FOIL Method
     
  • Vertical Method

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4.What is the difference between a binomial and a monomial?

A monomial has only one term, whereas a binomial has two terms.

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5.Do we always get a trinomial when we multiply two binomials?

Multiplying two binomials of degree 1 typically results in a quadratic polynomial, which may be a trinomial or binomial after combining like terms.

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