Variables and Algebraic Expressions Practice Problems

Master variables and algebraic expressions with step-by-step practice problems. Build confidence in evaluating expressions, combining like terms, and solving real-world algebra applications.

📚What You'll Master in This Practice Session
  • Identify and define variables in mathematical expressions and word problems
  • Evaluate algebraic expressions by substituting given values for variables
  • Simplify expressions by combining like terms and using distributive property
  • Translate word problems into algebraic expressions using appropriate variables
  • Apply order of operations when working with complex algebraic expressions
  • Solve real-world problems using variables and algebraic thinking skills

Understanding Equivalent Expressions

Complete explanation with examples

In previous articles, we have talked about what an algebraic expression is and how to get the numerical value of algebraic expressions. Today, we will cover equivalent expressions.

Equivalent expressions are two or more algebraic expressions that represent the same value. They may have a different structure, but their numerical value will be the same.

For example, in the following equation both sides represent the same quantity:

9X=3X+6X 9X=3X+6X

Below is another example with 2 variables. By simplifying the expressions on both sides of the equation, we can work out that on both we have 2X−3Y+5 2X-3Y+5 and therefore the expressions are equivalent.

2X−3Y+5=X+X−2Y+10−5−Y 2X-3Y+5=X+X-2Y+10-5-Y

Detailed explanation

Practice Equivalent Expressions

Test your knowledge with 14 quizzes

\( 13a+14b+17c-4a-2b-4b=\text{?} \)

Examples with solutions for Equivalent Expressions

Step-by-step solutions included
Exercise #1

Are the expressions the same or not?

18x 18x

2+9x 2+9x

Step-by-Step Solution

To determine if the expressions 18x 18x and 2+9x 2 + 9x are equivalent, we'll analyze their structures.

  • 18x 18x is a linear expression with a single term involving the variable x x , and its coefficient is 18.
  • 2+9x 2 + 9x consists of two terms: a constant term 2 2 and a linear term 9x 9x with coefficient 9.

For two expressions to be equivalent, each corresponding term must be equal. Here, the expression 18x 18x has no constant term, whereas 2+9x 2 + 9x has a constant term of 2. Furthermore, the linear term coefficients differ: 18≠9 18 \neq 9 .

Therefore, the expressions 18x 18x and 2+9x 2 + 9x are not the same. They structurally differ and cannot be made equivalent just through similar values of x x .

Therefore, the solution to this problem is: No.

Answer:

No

Video Solution
Exercise #2

Are the expressions the same or not?

20x 20x

2×10x 2\times10x

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Simplify the expression 2×10x 2 \times 10x .
  • Step 2: Compare the simplified expression with 20x 20x .

Now, let's work through each step:
Step 1: The expression 2×10x 2 \times 10x can be rewritten using associativity as 2×(10×x) 2 \times (10 \times x) .
Step 2: Apply the associative property of multiplication: (2×10)×x=20×x=20x (2 \times 10) \times x = 20 \times x = 20x .

Comparing this with the given expression, we see that both expressions are indeed the same, as they simplify to 20x 20x .

Therefore, the solution to the problem is Yes.

Answer:

Yes

Video Solution
Exercise #3

Are the expressions the same or not?

3+3+3+3 3+3+3+3

3×4 3\times4

Step-by-Step Solution

To solve this problem, we'll analyze the expressions 3+3+3+33+3+3+3 and 3×43 \times 4 to determine if they are equivalent.

First, evaluate the expression 3+3+3+33+3+3+3:

  • Add the numbers: 3+3=63 + 3 = 6
  • Add again: 6+3=96 + 3 = 9
  • Add the last 33: 9+3=129 + 3 = 12

The result of 3+3+3+33+3+3+3 is 1212.

Next, evaluate the expression 3×43 \times 4:

  • Perform the multiplication: 3×4=123 \times 4 = 12

The result of 3×43 \times 4 is also 1212.

Since both expressions result in the same number, we conclude that

The expressions are the same.

Therefore, the correct answer is Yes.

Answer:

Yes

Video Solution
Exercise #4

11+5x−2x+8= 11+5x-2x+8=

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Identify the like terms in the expression.
  • Step 2: Combine the constant terms.
  • Step 3: Combine the coefficients of xx.

Now, let's work through each step:
Step 1: The given expression is 11+5x−2x+811 + 5x - 2x + 8. There are constants (11 and 8) and terms with xx (5x and -2x).
Step 2: Combine the constants: 11+8=1911 + 8 = 19.
Step 3: Combine the coefficients of xx: 5x−2x=3x5x - 2x = 3x.

After simplification, the expression becomes 19+3x19 + 3x.

The correct solution from the multiple-choice options is 19+3x\boxed{19 + 3x}.

Answer:

19+3X

Video Solution
Exercise #5

3x+4x+7+2=? 3x+4x+7+2=\text{?}

Step-by-Step Solution

Let's simplify the expression 3x+4x+7+2 3x + 4x + 7 + 2 step-by-step:

  • Step 1: Combine Like Terms Involving x x
    The terms 3x 3x and 4x 4x are like terms because both involve the variable x x . To combine them, add their coefficients:
    3x+4x=(3+4)x=7x 3x + 4x = (3 + 4)x = 7x

  • Step 2: Combine Constant Terms
    The expression includes constant terms 7 7 and 2 2 . These can be added together to simplify:
    7+2=9 7 + 2 = 9

  • Step 3: Write the Simplified Expression
    Now, combine the results from Step 1 and Step 2 to form the final simplified expression:
    7x+9 7x + 9

Therefore, the simplified expression is 7x+9 7x + 9 .

Reviewing the choices provided, the correct choice is:

  • Choice 2: 7x+9 7x + 9

This matches our simplified expression, confirming our solution is correct.

Answer:

7x+9 7x+9

Video Solution

Frequently Asked Questions

What is a variable in algebra and how do I use it?

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A variable is a letter (like x, y, or n) that represents an unknown number or value that can change. You use variables to write expressions and equations that can solve many different problems at once, making math more flexible and powerful.

How do you evaluate algebraic expressions step by step?

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To evaluate an algebraic expression: 1) Substitute the given numbers for each variable, 2) Follow the order of operations (PEMDAS), 3) Simplify by performing calculations from left to right. For example, if x = 3 in 2x + 5, substitute to get 2(3) + 5 = 11.

What does combining like terms mean in algebra?

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Combining like terms means adding or subtracting terms that have the same variable raised to the same power. Like terms examples: 3x and 5x can combine to 8x, but 3x and 5y cannot be combined because they have different variables.

How do I write algebraic expressions from word problems?

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Key steps for writing expressions from word problems: • Identify what the variable represents • Look for operation keywords (sum = +, difference = -, product = ×, quotient = ÷) • Translate phrases like 'five more than x' to 'x + 5' • Practice with simple examples first

What are common mistakes when working with variables?

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Common variable mistakes include: forgetting to multiply coefficients with variables (2x means 2 × x), trying to combine unlike terms (x + y ≠ xy), and mixing up substitution order. Always double-check your variable substitutions and follow order of operations carefully.

Why are algebraic expressions important in real life?

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Algebraic expressions help solve real-world problems like calculating costs, distances, and measurements that change. They're used in budgeting (total cost = price × quantity), science formulas, and any situation where you need to find unknown values.

What grade level learns variables and algebraic expressions?

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Variables and basic algebraic expressions are typically introduced in 6th-7th grade, with more complex applications in 8th grade and Algebra 1. The concepts build gradually from simple substitution to multi-step expression evaluation and real-world problem solving.

How can I remember the order of operations with variables?

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Use PEMDAS (Parentheses, Exponents, Multiplication/Division, Addition/Subtraction) just like with regular numbers. Remember that variables follow the same rules: 2x + 3x = 5x, and 2(x + 3) = 2x + 6 using the distributive property.

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