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Introduction
Exponent Rules helps you connect a mathematical rule to a result you can explain and check. Choose the correct exponent law for a product, quotient, or repeated power. State all restrictions from zero or negative exponents. This lesson belongs to exponents and polynomials and builds toward independent Algebra I problem solving.
Alignment uses 19 TAC §111.39(c). Review lessons sample their listed standards. Readiness and supporting labels describe STAAR emphasis, not whether a topic is required.
Learning objectives
- Identify the quantities and representations used in exponent rules.
- Apply the lesson's rule to solve a numerical or contextual problem.
- Explain each mathematical step using the correct vocabulary.
- Verify an answer and correct a likely error.
Prerequisite knowledge
Multiply, divide, and interpret repeated factors.
Previous lesson: Writing Systems from Tables and Graphs
Key mathematical vocabulary
- domain
- The set of permitted inputs.
- exponent
- A number specifying a power.
- factor
- An expression multiplied by another to form a product.
- root
- A solution of an equation.
- ratio
- A comparison by division.
Formulas and rules
- am · an=am+n
- am/an=am−n, a≠0
- (am)n=amn
Laws of exponents
Choose the correct exponent law for a product, quotient, or repeated power. State all restrictions from zero or negative exponents.
For a nonzero base, am·an=am+n, am/an=am−n, and (am)n=amn for integer exponents. The first laws count repeated factors; division cancels common nonzero factors.
A nonzero base to exponent zero is 1, and a negative exponent represents a reciprocal. Rational exponents connect powers with roots: ap/q is the qth root followed by the pth power, subject to real-number domain restrictions. Even roots require nonnegative radicands; negative powers also exclude zero.
A method you can explain
- Read the question and identify the known information, unknown quantities, and any domain restrictions. Select a suitable representation and tool.
- Apply the relationship explained above. Repeated factors of the same base combine into one product.
- Write each calculation or logical inference on a separate line. Keep units and signs visible. When two methods are possible, compare which one uses the given information most directly.
- Check the result in the ORIGINAL conditions, not merely the last simplified line. At x=2, repeated multiplication verifies the exponent law.
- Interpret what the answer means. Decide whether its size, sign, and precision make sense; identify a restriction or assumption that would change the conclusion.
Five worked examples
Example 1 · Beginner
Simplify x6 · x7.
- Repeated factors of the same base combine into one product.
- Add exponents: 6+7=13.
- Keep the base unchanged: x13. Exponent laws do not combine sums such as x²+x³.
Answer: x13
Verify: At x=2, repeated multiplication verifies the exponent law.
Avoid this mistake: Adding exponents when taking a power of a power: multiply them.
Example 2 · Basic
Simplify x7 · x7.
- Repeated factors of the same base combine into one product.
- Add exponents: 7+7=14.
- Keep the base unchanged: x14. Exponent laws do not combine sums such as x²+x³.
Answer: x14
Verify: At x=2, repeated multiplication verifies the exponent law.
Avoid this mistake: Treating a negative exponent as a negative answer.
Example 3 · Intermediate
Simplify x8 · x7.
- Repeated factors of the same base combine into one product.
- Add exponents: 8+7=15.
- Keep the base unchanged: x15. Exponent laws do not combine sums such as x²+x³.
Answer: x15
Verify: At x=2, repeated multiplication verifies the exponent law.
Avoid this mistake: Applying product rules to a sum of powers.
Example 4 · Advanced
Simplify x9 · x7.
- Repeated factors of the same base combine into one product.
- Add exponents: 9+7=16.
- Keep the base unchanged: x16. Exponent laws do not combine sums such as x²+x³.
Answer: x16
Verify: At x=2, repeated multiplication verifies the exponent law.
Avoid this mistake: Adding exponents when taking a power of a power: multiply them.
Example 5 · Challenge
Simplify x2 · x8.
- Repeated factors of the same base combine into one product.
- Add exponents: 2+8=10.
- Keep the base unchanged: x10. Exponent laws do not combine sums such as x²+x³.
Answer: x10
Verify: At x=2, repeated multiplication verifies the exponent law.
Avoid this mistake: Treating a negative exponent as a negative answer.
Common mistakes and corrections
- Adding exponents when taking a power of a power: multiply them.
- Treating a negative exponent as a negative answer.
- Applying product rules to a sum of powers.
Real-world applications
- Write repeated scale factors efficiently. Define the input and its units, apply the mathematical relationship, and check that the result fits the setting.
- Compare growth over several equal time periods. Define the input and its units, apply the mathematical relationship, and check that the result fits the setting.
Topic summary
Choose the correct exponent law for a product, quotient, or repeated power. State all restrictions from zero or negative exponents.
For a nonzero base, am·an=am+n, am/an=am−n, and (am)n=amn for integer exponents. The first laws count repeated factors; division cancels common nonzero factors.
Frequently asked questions
What should I know before exponent rules?
Multiply, divide, and interpret repeated factors.
How can I check my work?
At x=2, repeated multiplication verifies the exponent law. A numerical check can detect an error; when claiming an identity for all inputs, also explain the algebraic property that makes it true.
Which mistakes should I watch for?
Adding exponents when taking a power of a power: multiply them. Treating a negative exponent as a negative answer. Applying product rules to a sum of powers.
Can I use another valid method?
Yes. Explain your assumptions, show enough intermediate work to justify the result, and verify it in the original problem. Equivalent expressions and valid alternative methods receive credit.
Mathematical process practice · A.1A–A.1G
- A.1A: Write repeated scale factors efficiently.
- A.1B: Plan, solve, check, and interpret the written response.
- A.1C: Select paper, a calculator, a table, or a graph; explain the choice.
- A.1D: Connect symbols with a verbal explanation and another representation.
- A.1E: Organize the solution with a table, diagram, or labeled equations.
- A.1F: Explain how the representation and the algebraic rule express the same relationship.
- A.1G: Justify each operation and the reasonableness of the conclusion.
Quick revision notes
- Choose the correct exponent law for a product, quotient, or repeated power. State all restrictions from zero or negative exponents.
- Adding exponents when taking a power of a power: multiply them.
- Treating a negative exponent as a negative answer.
- Applying product rules to a sum of powers.
Practice and explain
Try all four multiple-choice questions, then show your reasoning in the written response. Objective scores and AI feedback assess different skills.
Continue learning
Original Cambridge Veritas practice. These are not official STAAR items. Cambridge Veritas is not affiliated with or endorsed by TEA.
Official Algebra I TEKS (§111.39) · TEA assessed curriculum · STAAR blueprint · TEA instructional materials