8.3 - Multiplying a Monomial by a Monomial
Enroll to start learning
You’ve not yet enrolled in this course. Please enroll for free to listen to audio lessons, classroom podcasts and take practice test.
Interactive Audio Lesson
Listen to a student-teacher conversation explaining the topic in a relatable way.
Understanding Monomials
🔒 Unlock Audio Lesson
Sign up and enroll to listen to this audio lesson
Today, we will start by discussing monomials. Can anyone define what a monomial is?
Is it just an expression with only one term?
Exactly! A monomial consists of a single term, such as `3xy`, `-5`, or `4x^2y`.
What happens when we multiply two monomials?
Great question! When we multiply two monomials, we multiply their coefficients and apply the rules of exponents to the variables.
Can you give an example?
Sure! For instance, if we multiply `4x` and `3y`, we get `12xy`. See how simple that was?
So we just combine the numbers in front and keep the variables together?
Exactly! Let's summarize: when multiplying monomials, multiply coefficients and add the exponents of like variables. Now, let's move to our next point.
Multiplying Multiple Monomials
🔒 Unlock Audio Lesson
Sign up and enroll to listen to this audio lesson
Now, let’s delve into multiplying three or more monomials. What happens then?
Do we just keep multiplying them together?
Exactly! For example, if we have `2x`, `5y`, and `7z`, we multiply their coefficients together: `2 × 5 × 7 = 70`, and write the variables together, resulting in `70xyz`.
Does the order matter when multiplying?
Not at all! Multiplication is commutative, so `2x × 5y × 7z` is the same as `7z × 2x × 5y`.
So I can group them however I want?
Yes, you can! This flexibility is advantageous. Let’s summarize these rules before we practice.
Working with Examples
🔒 Unlock Audio Lesson
Sign up and enroll to listen to this audio lesson
Let's review some examples to cement our understanding. What is the product of `5x` and `4x²`?
That would be `20x³`, right?
That's correct! Now, how about `3x` multiplied by `-5y`?
It’s `-15xy`!
Excellent! You are really getting the hang of this. Let's recap: multiply coefficients and apply exponent rules. Ready for some practice?
Introduction & Overview
Read summaries of the section's main ideas at different levels of detail.
Quick Overview
Standard
Section 8.3 explores the multiplication of monomials, explaining how to multiply two or more monomials step-by-step. It highlights the result of multiplying monomials, including the combination of coefficients and variables. Examples demonstrate multiplying monomials effectively and efficiently, providing a strong foundation for further algebraic expression operations.
Detailed
Detailed Overview of Multiplying a Monomial by a Monomial
In this section, we focus on the foundational operation of multiplying monomials, which are algebraic expressions that contain only one term.
Definition
A monomial is defined as an expression that includes only one term, upon which we can perform multiplication in a systematic manner. For example, monomials may appear as simple numbers (like 4 or -3) or variable expressions (like 3xy or -15abc).
Key Points:
-
Multiplying Two Monomials: The product of two monomials results in another monomial. The general rule involves multiplying the coefficients (numerical parts) while applying the rules of exponents for the variable parts.
- Examples:
- If we multiply
xwith3y, we write:
x × 3y = 3xy. - Multiplying
5xwith4x², we find:
5x × 4x² = (5 × 4) × (x × x²) = 20x³.
- If we multiply
- Examples:
-
Example with Negative Coefficients: For instance,
5x × (–3y)gives us–15xy. -
Multiplying Three Monomials: The multiplication rules extend to three or more monomials. Combine coefficients first, and then variables:
2x × 5y × 7z = (2 × 5 × 7)(x × y × z) = 70xyz. - The associative property allows various groupings during multiplication, giving us consistency regardless of how we organize the expressions for calculations.
Conclusion
Understanding how to multiply monomials sets the groundwork for more advanced operations in algebra, such as working with polynomials, where the same foundational principles apply.
Youtube Videos
Audio Book
Dive deep into the subject with an immersive audiobook experience.
Understanding Monomials
Chapter 1 of 4
🔒 Unlock Audio Chapter
Sign up and enroll to access the full audio experience
Chapter Content
Expression that contains only one term is called a monomial.
Detailed Explanation
A monomial is an algebraic expression that consists of a single term. This means it contains a coefficient (a numerical factor) multiplied by one or more variables raised to non-negative integer exponents. For example, 3x, -5ab^2, and 7 are all monomials. It is important to recognize that a monomial cannot have addition or subtraction within it; it must be a product.
Examples & Analogies
Think of a monomial like a single item in a shopping cart. Just as you can have an apple (which represents 1 apple) or 3 apples (3x), you can't have a mixture of items (like an apple and a banana together in this case) in the same cart without making it more complex.
Multiplying Two Monomials
Chapter 2 of 4
🔒 Unlock Audio Chapter
Sign up and enroll to access the full audio experience
Chapter Content
We begin with
4 × x =x + x + x + x = 4x as seen earlier.
Similarly, 4 × (3x) = 3x + 3x + 3x + 3x = 12x.
Now, observe the following products.
(i) x × 3y = x × 3 × y = 3 × x × y = 3xy
(ii) 5x × 3y = 5 × x × 3 × y = 5 × 3 × x × y = 15xy
(iii) 5x × (–3y) = 5 × x × (–3) × y = 5 × (–3) × x × y = –15xy
Detailed Explanation
When multiplying two monomials, you multiply their coefficients (numerical parts) and then combine the variables by adding their exponents. For example, to multiply 4 and 3x, you would multiply the numbers (4 * 3 = 12) and keep the variable x as is, resulting in 12x. In a more complex example like 5x * 3y, you multiply 5 * 3 = 15 and then multiply x * y, resulting in 15xy. If there is a negative coefficient, like in 5x * (-3y), it results in -15xy.
Examples & Analogies
Imagine you’re packing boxes. If one box can contain 5 toys (5x) and you want to pack 3 such boxes (3y), you can think of multiplying the contents of the boxes. So, 5 toys/box * 3 boxes = 15 toys total, which can be represented as 15xy where x could represent toys and y represents boxes.
More Examples of Multiplying Monomials
Chapter 3 of 4
🔒 Unlock Audio Chapter
Sign up and enroll to access the full audio experience
Chapter Content
Some more useful examples follow.
Note that 5 × 4 = 20
(iv) 5x × 4x2 =(5 × 4) × (x × x2) = 20 × x3 = 20x3
(v) 5x × (– 4xyz) =(5 × – 4) × (x × xyz) = –20 × (x × x × y × z) = –20x2yz
(i.e., algebraic factor of product = algebraic factor of first monomial × algebraic factor of second monomial.)
Detailed Explanation
When you multiply monomials that have the same base variables, you add their exponents. For instance, in 5x * 4x^2, you first multiply the coefficients 5 * 4 = 20 and then for the variable x, you add the exponents. Here it is x^(1+2) = x^3, so the result is 20x^3. Similarly, when multiplying different variables, make sure to keep track of each part to know how it combines, as shown in the example with -20x^2yz.
Examples & Analogies
Think of it this way: if one carton holds 5 apples (5x), and you have 4 cartons stacked, where each carton has an extra space for the same type of apple stacked on top (4x^2), you can multiply those numbers to know how many total apples you can fill in for that space. It’s like arranging in a grid: stack vertically to get more apples in that volume.
Multiplying Three or More Monomials
Chapter 4 of 4
🔒 Unlock Audio Chapter
Sign up and enroll to access the full audio experience
Chapter Content
Observe the following examples.
(i) 2x × 5y × 7z = (2x × 5y) × 7z = 10xy × 7z = 70xyz
(ii) 4xy × 5x2y2 × 6x3y3 = (4xy × 5x2y2) × 6x3y3 = 20x3y3 × 6x3y3 = 120x3y3 × x3y3 = 120(x3 × x3)(y3 × y3) = 120x6y6.
Detailed Explanation
When multiplying multiple monomials together, group the multiplications in stages if needed. For example, in 2x * 5y * 7z, you can first multiply 2x and 5y to get 10xy, then multiply that result by 7z to get 70xyz. You can also combine coefficients and the variables separately to ensure easier calculations. Notice that when multiplying monomials with the same variables, you should add their exponents.
Examples & Analogies
Consider a factory where you make toy sets. If one type of toy (2x) can be combined with another type (5y) and then that entire result can be styled or packaged with yet another variant (7z), you can see how the products multiply together to form larger combinations in toy sets, similar to multiplying numbers and keeping track of distinct features.
Key Concepts
-
Monomial: A single-term algebraic expression.
-
Coefficient: The number before a variable.
-
Exponent Rule: When multiplying like bases, add exponents.
Examples & Applications
Example 1: Multiply 5x and 4x² to get 20x³.
Example 2: Multiply 6a and -3a to get -18a².
Memory Aids
Interactive tools to help you remember key concepts
Rhymes
When monomials align, just combine; multiply the numbers, keep the variables in line.
Stories
Imagine multiplying apples and oranges. The apples, like coefficients, multiply, while the oranges represent variables. They come together to form a tasty fruit salad!
Memory Tools
CAVEMAN: Coefficients All Value Each Monomial's Amount - to remember the steps to multiply monomials correctly.
Acronyms
MAMP
Multiply And Match Products - a reminder to ensure you multiply coefficients and match variables properly.
Flash Cards
Glossary
- Monomial
An algebraic expression that contains only one term.
- Coefficient
The numerical factor in a term.
- Exponent
A number that indicates how many times a base is multiplied by itself.
Reference links
Supplementary resources to enhance your learning experience.