Expressions and Properties
A free Algebra I lesson from the “Algebra Foundations” unit, with a worked example and practice problems including step-by-step solutions.
Algebraic expressions use variables to represent unknown or changing values. Like terms have the same variable part. The distributive property lets you multiply a factor across terms inside parentheses.
What you'll learn
- Identify terms and coefficients
- Apply the distributive property
- Combine like terms
Why it matters: Spreadsheet formulas, coding expressions, and order totals use variables and grouped terms to keep changing quantities organized.
Worked example
Problem. Simplify 3(x + 4) + 2x.
- Distribute 3 across x + 4 to get 3x + 12.
- Combine like terms: 3x + 2x = 5x.
- The simplified expression is 5x + 12.
Answer: 5x + 12
Practice problems
1. In 9x - 4, what is the coefficient of x?
Choices: 9 · x · -4 · 5
Show solution
- Warm-up: First identify exactly what the question is asking: In 9x - 4, what is the coefficient of x?
- Compare each answer choice with the calculation or rule, and eliminate choices that do not satisfy the condition.
- The coefficient is the number multiplying the variable.
- In 9x, the coefficient is 9.
- Verify the selected choice by checking that it satisfies the original prompt and that the other choices fail the same test.
Answer: 9
2. Simplify 4x + 7x.
Show solution
- Warm-up: First identify exactly what the question is asking: Simplify 4x + 7x.
- Choose the operation or relationship that matches the wording, then carry it out one clear step at a time.
- Both terms are like terms.
- Add the coefficients: 4 + 7 = 11.
- Check the result by substituting or estimating: the response should match 11x and make sense in the original problem.
Answer: 11x
3. Simplify 12 - 5 + 3x.
Show solution
- Warm-up: First identify exactly what the question is asking: Simplify 12 - 5 + 3x.
- Choose the operation or relationship that matches the wording, then carry it out one clear step at a time.
- Combine constants: 12 - 5 = 7.
- The variable term stays 3x.
- Check the result by substituting or estimating: the response should match 3x + 7 and make sense in the original problem.
Answer: 3x + 7
4. Simplify 2(x + 5).
Show solution
- Core Practice: First identify exactly what the question is asking: Simplify 2(x + 5).
- Choose the operation or relationship that matches the wording, then carry it out one clear step at a time.
- Distribute 2 to each term.
- 2 times x is 2x and 2 times 5 is 10.
- Check the result by substituting or estimating: the response should match 2x + 10 and make sense in the original problem.
Answer: 2x + 10
5. Simplify 5(2x - 3).
Show solution
- Core Practice: First identify exactly what the question is asking: Simplify 5(2x - 3).
- Choose the operation or relationship that matches the wording, then carry it out one clear step at a time.
- Distribute 5.
- 5 times 2x is 10x and 5 times -3 is -15.
- Check the result by substituting or estimating: the response should match 10x - 15 and make sense in the original problem.
Answer: 10x - 15
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