Combining Like Terms and Distributive Property

Combining Like Terms and Distributive Property

Unit Overview

In this unit, students will explore how to solve linear equations by combining like terms, using the distributive property, and identifying the number of solutions for the equations.

Key Words

Term: A number, a variable(s), or a number and a variable(s) multiplied together. Terms are separated by a positive (+) or negative (-) sign.

Constant: A number by itself with no variable.

Coefficient: The number being multiplied by the variable.

Like Terms: Terms that have identical variable(s).

Unlike Terms: Terms that do not have identical variable(s).

Click on each word to see an example: Term, Constant, Coefficient, Like Terms, Unlike Terms.

Understanding Like and Unlike Terms in Algebra

In algebra, terms are the basic components of expressions. A term can be a single number (a constant), a variable (like x or y), or a combination of numbers and variables multiplied together. Terms are separated by addition (+) or subtraction (-) signs in an expression. Understanding the distinction between like and unlike terms is crucial as it helps in simplifying expressions and solving algebraic equations effectively.

Defining Like Terms

Like terms are terms that have exactly the same variable components raised to the same powers. The coefficients (the numbers multiplying the variables) do not need to be the same. For instance, in the expression 3x2 + 5x2, both terms are like terms because they contain the same variable x raised to the same power (2).

Examples of like terms include:

  • 7xy and -2xy (same variables x and y with no powers)
  • 4a3b2 and -9a3b2 (same variables a and b, a raised to the 3rd power, and b to the 2nd power)

Defining Unlike Terms

Unlike terms, on the other hand, are terms that have different variable parts or exponents. The difference might be in the variable itself or in the exponent of the same variable. For example, 3x2 and 5x3 are unlike terms because, even though they both contain the variable x, the powers are different.

More examples include:

  • x2 and y2 (different variables)
  • 2ab and 2ba2 (same variables but different powers)
  • 5x and 5y (different variables)

Simplifying Expressions Using Like and Unlike Terms

Simplifying algebraic expressions often involves combining like terms. This process is called "collecting like terms." For example, in the expression 4x + 3x2 - 2x, you can combine the like terms 4x and -2x to simplify the expression to 2x + 3x2.

When dealing with unlike terms, remember that they cannot be combined through addition or subtraction due to their different variable parts or exponents. Each term stands alone in the expression.

Expression Like or Unlike?
3x and 5x Like
2x² and 3x Unlike
7y and -7y Like
4ab and 4ba Like
5m and 5n Unlike

Practice entering 'like' or 'unlike' for the following expressions:

3x and 2x

5x and 5y

6a and 6a

4bc and 4cb

7x² and 7x

 

Combining Like Terms in Algebra

Combining like terms is a critical process in algebra that involves simplifying algebraic expressions by adding or subtracting terms that are alike. Terms are considered 'like' if they have identical variable parts, including the variables and their exponents.

 

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Why Combine Like Terms?

The primary reason for combining like terms is to simplify an expression, making it easier to handle and solve equations. Simplification can help in solving equations, evaluating expressions, and understanding algebraic relationships more clearly.

How to Identify Like Terms

Like terms have the same variable factors. For example, 2x2y and 5x2y are like terms because both contain the same variables x and y, with x raised to the 2nd power. However, 2xy and 2x2y are not like terms because the exponent of x differs.

Examples of Combining Like Terms

Consider the expression 3x + 4x - 2x + 5. Here, all the terms involving x are like terms. They can be combined as follows:

  • 3x + 4x - 2x = 5x

The simplified expression is 5x + 5.

Steps to Combine Like Terms

  1. Identify all like terms in the expression.
  2. Add or subtract the coefficients of these like terms while keeping the variable part unchanged.
  3. Rewrite the expression with the combined like terms.

Practical Example

Let's simplify the expression 6a2b - 3ab2 + 2a2b + 4ab2:

  • Combine like terms 6a2b and 2a2b: 6a2b + 2a2b = 8a2b
  • Combine like terms -3ab2 and 4ab2: -3ab2 + 4ab2 = 1ab2

The simplified expression is 8a2b + ab2.

Combining like terms is fundamental in algebra for simplifying expressions and solving equations more efficiently. It helps to create clearer and less complex expressions which are crucial for advanced algebraic operations and calculus.

Expression Simplified
3x + 2x 5x
4a + 6a 10a
7y - 2y 5y
5b + 3b + 2b 10b
9m - 4m 5m

Practice simplifying the following expressions:

5x + 3x

6y + 2y - 3y

10z - 6z

12a + 7a + 1a

9m - 5m + 4m

Distributive Property in Algebra

The Distributive Property, also known as the distributive law of multiplication over addition, is a crucial algebraic property used to simplify expressions and solve equations. It states that multiplying a sum by a number is the same as multiplying each addend of the sum by the number and then adding the results.

Formula of the Distributive Property

The formula for the distributive property can be expressed as follows:

a(b + c) = ab + ac

Why Use the Distributive Property?

This property is particularly useful for simplifying expressions that involve parentheses and are not immediately easy to add or subtract. It helps in breaking down complex problems into simpler parts that are easier to manage and solve.

Examples of the Distributive Property

Consider the expression 3(2 + 4). Applying the distributive property, we multiply 3 by each addend inside the parentheses:

  • 3(2 + 4) = 3×2 + 3×4 = 6 + 12 = 18

This simplifies the expression to 18, demonstrating how the distributive property aids in multiplication across a sum.

Application in Variable Expressions

The distributive property is also invaluable when dealing with variable expressions. For example:

  • 5(x + 3) = 5x + 15
  • 2(a + 7) = 2a + 14

Complex Example

Let’s apply the distributive property to a more complex expression: 4(x + 2y - 3z). Multiplying 4 by each term within the parentheses gives:

  • 4(x + 2y - 3z) = 4x + 8y - 12z

This demonstrates how the property simplifies expressions involving multiple terms and different operations.

The distributive property is essential for simplifying and solving algebraic equations, making it a foundational element in algebra and beyond. Understanding and applying this property allows for more efficient and accurate problem-solving in mathematics.

Expression Simplified
2(3x + 4) 6x + 8
5(2y + 3) 10y + 15
3(4z - 2) 12z - 6
4(1a + 2b) 4a + 8b
6(1m - 3n) 6m - 18n

Practice applying the distributive property to these expressions:

3(2x + 4)

4(3y + 5)

5(2z - 3)

2(4a + 6b)

7(3m + 2n)