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Last updated on September 29, 2025

Multiplying Monomial

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Multiplying monomials is an algebraic operation that is similar to multiplying integers, but the rule of adding exponents for variables with the same base. In this article, we will learn to multiply monomials with polynomials.

Multiplying Monomial for US Students
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What are monomials?

A monomial is an algebraic expression of a single term that is made up of a number, a variable, or a combination of both. In monomials, the exponents of the variables must be whole numbers, such as 0, 2, 4, and so on.
 

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What are Multiplying Monomials?

Multiplying monomials is the method for multiplying a monomial by each term of a polynomial, such as a binomial or trinomial. This process uses the distributive property, meaning you multiply the monomial by each term inside the polynomial. When multiplying multiple polynomials, multiply the coefficients, which means numbers, and add the exponents (powers x2) of the same variables in the expression.
 

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Multiplication of Monomial by a Monomial

In the multiplication of a monomial by a monomial, the result is also a monomial. A monomial has only one term in the algebraic expression. While solving the problem, first multiply the coefficients of monomials, then add the exponents of any variable that are the same. For example, multiply the monomials of 2x5 by 5x2.
First, multiply the coefficients = 2 × 5 = 10
Then add the exponents that the variable has = x5 × x2 = x5 + 2 = x7
The solution is 10x7.

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Multiplication of Monomial by a Binomial

A binomial has two terms in the expression, which are separated by operations like addition or subtraction. For example, 3x × (4x + 5)
First multiply 3x × 4x = 12x2 (x1 × x1 = x2)
Then multiply 3x × 5 = 15x

The final expression is 12x2 + 15x
 

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Multiplication of Monomial by a Trinomial

A trinomial, which has three terms in algebraic expressions, is separated by operations like addition and subtraction. When multiplying a monomial by a trinomial, we should follow the distributive law of multiplication. For example, 2x × (x + 3x2 + 5)
First multiply 2x  × x = 2x2 (x1× x1 = x1+1 = x2)
Then 2x  × 3x2 = 6x3
2x  × 5 = 10x
The final expression is 2x2 + 6x3 + 10x
 

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Real Life Applications of Multiplying Monomials

Multiplying monomials looks like a simple algebraic operation, but it plays a role in solving practical problems across fields. Here are some real-life applications given below.

  • Land Management: In agriculture, farmers use monomial multiplication to calculate the total land area or resource needs. For example, one monomial may represent the dimension of the plot, and another monomial represents the number of plots or required quantity per unit area
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  •  Construction and Architecture:  Architects and builders use multiplying monomials when calculating the volume, area, or cost of construction materials. Multiplying monomials helps in scaling models, budgeting, and adjusting project requirements depending on variable inputs.
  • Inventory Management: Businesses use monomial multiplication to calculate the total cost or revenue by multiplying the price per item by the quantity in the stock. 
  • Physics:  In physics, many formulas involve multiplying quantities such as force, distance, or time, which are represented by monomials.
  • Engineering:  Engineers use monomial multiplication to calculate quantities such as work, energy, or resistance in circuits. Keeping the expressions in general form until specific values are substituted makes the calculation adaptable and scalable across different scenarios.
     
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Common Mistakes and How to Avoid Them in Multiplying Monomials

Multiplying monomials is easy to understand, but students often make simple errors that can lead to incorrect results. Here are some mistakes and how to avoid them.

Mistake 1

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Adding the coefficients instead of multiplying

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Students often add the coefficients instead of multiplying. Always multiply the coefficients. For example, 2x × 4x = 8x2 not 6x2
 

Mistake 2

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Multiplying the different variables as if they were the same
 

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Some students mistakenly combine unlike variables like x and y as if they were the same. Only add the exponents of variables that have the same base.

Mistake 3

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Forgetting to add the exponents
 

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 Some students multiply the variables correctly, but overlook adding their exponents. Always remember to add the exponents of terms with the same base when multiplying.
 

Mistake 4

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Ignoring the signs
 

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Sometimes students multiply the coefficients and leave out the signs, which leads to incorrect answers. Always include the signs while multiplying.
 

Mistake 5

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Multiplying the exponents instead of adding
 

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 Students mistakenly multiply the exponents the same way they multiply the coefficients, which is wrong. The correct one is to add the exponents when multiplying terms with the same base.
 

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Solved Examples on Multiplying Monomial

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Problem 1

Multiply the monomials 3x2 and 4x3

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Okay, lets begin

12x5
 

Explanation

First, multiply the coefficients = 3 × 4 = 12
Then add the exponents = x2  × x3 = x2+3 = x5
Combine both
12x5
The product of monomials is 3x2 and 4x3 is 12x5
 

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Problem 2

Find the product of -2a3b and 5 a3b2

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Okay, lets begin

-10a6b3
 

Explanation

First step: multiply the coefficients: -2 × 5 = -10
Then add the exponents of a and b
a3 × a3 = a6
b × b2 = b3
Final product is: -10a6b3
 

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Problem 3

Multiply the monomials 7xy2 and -3x2y2

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Okay, lets begin

-21x3y4
 

Explanation

First, multiply the coefficients = 7 × -3 = -21
Then add the exponents of x and y
x × x2 = x3
y2 × y2 = y4
Combine both
-21x3y4
 

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Problem 4

Multiply the monomials 2m2n3 and 4mn2

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Okay, lets begin

8m3n5
 

Explanation

First, multiply the coefficients = 2 × 4 = 8
Add the exponents:
m2 × m = m3.
n3 × n2 = n5
Finally, combine the terms
8m3n5
 

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Problem 5

Find the product of -5x4y2 and 2x2y

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Okay, lets begin

-10x6y3
 

Explanation

Multiply the coefficients -5 × 2 = -10
Then add the exponents:
x4 × x2 = x6
y2 × y = y3
Combine both like terms:
 -10x6y3
 

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FAQs on Multiplying Monomial

1.What is the meaning of multiplying monomials?

Multiplying monomials involves applying exponent addition and multiplication rules to simplify expressions.
 

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2.How to multiply a monomial by a monomial?

First, multiply the coefficient
Then multiply the variables by adding the exponents
Then combine like terms if necessary.

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3.Can we add the exponents of different variables?

No, we can’t add the exponents of different variables. 
 

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4.How to multiply a monomial by a trinomial?

Multiply the monomial by each term in the trinomial using the distributive property, then simplify each result, and then combine like terms.
 

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5.Give the steps for multiplying a monomial by a binomial

Multiply the monomial by each term of the binomial using the distributive property, then simplify the terms.
 

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Jaskaran Singh Saluja

About the Author

Jaskaran Singh Saluja is a math wizard with nearly three years of experience as a math teacher. His expertise is in algebra, so he can make algebra classes interesting by turning tricky equations into simple puzzles.

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Fun Fact

: He loves to play the quiz with kids through algebra to make kids love it.

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