Learn on PengiThe Art of Problem Solving: Prealgebra (AMC 8)Chapter 4: Fractions

Lesson 4: Raising Fractions to Powers

In this Grade 4 lesson from The Art of Problem Solving: Prealgebra (AMC 8), students learn how to raise fractions to positive and negative integer powers by applying the rule (a/b)^n = a^n/b^n to both the numerator and denominator. The lesson also covers negative exponents with fractions, including how a negative exponent flips the fraction to its reciprocal before applying the power. Students practice these skills through problems that combine exponent laws to simplify complex fraction expressions.

Section 1

Quotient to a power property

Property

If aa and bb are real numbers, b0b \neq 0, and mm is a counting number, then

(ab)m=ambm\left(\frac{a}{b}\right)^m = \frac{a^m}{b^m}

To raise a fraction to a power, raise the numerator and denominator to that power.

Examples

  • To simplify (23)4\left(\frac{2}{3}\right)^4, you apply the exponent to both the numerator and the denominator: 2434=1681\frac{2^4}{3^4} = \frac{16}{81}.
  • To simplify (pq)7\left(\frac{p}{q}\right)^7, you raise both the numerator and denominator to the 7th power, resulting in p7q7\frac{p^7}{q^7}.

Section 2

Reciprocal Property for Fractions with Exponent -1

Property

When a fraction is raised to the power of -1, it equals the reciprocal of the original fraction:

(ab)1=ba\left(\frac{a}{b}\right)^{-1} = \frac{b}{a}

Examples

Section 3

Negative Exponents for Fractions

Property

When a fraction has a negative exponent, flip the fraction and make the exponent positive:

(ab)n=(ba)n=bnan\left(\frac{a}{b}\right)^{-n} = \left(\frac{b}{a}\right)^n = \frac{b^n}{a^n}

Examples

Book overview

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Chapter 4: Fractions

  1. Lesson 1

    Lesson 1: What is a Fraction?

  2. Lesson 2

    Lesson 2: Multiplying Fractions

  3. Lesson 3

    Lesson 3: Dividing by a Fraction

  4. Lesson 4Current

    Lesson 4: Raising Fractions to Powers

  5. Lesson 5

    Lesson 5: Simplest Form of a Fraction

  6. Lesson 6

    Lesson 6: Comparing Fractions

  7. Lesson 7

    Lesson 7: Adding and Subtracting Fractions

  8. Lesson 8

    Lesson 8: Mixed Numbers

Lesson overview

Expand to review the lesson summary and core properties.

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Section 1

Quotient to a power property

Property

If aa and bb are real numbers, b0b \neq 0, and mm is a counting number, then

(ab)m=ambm\left(\frac{a}{b}\right)^m = \frac{a^m}{b^m}

To raise a fraction to a power, raise the numerator and denominator to that power.

Examples

  • To simplify (23)4\left(\frac{2}{3}\right)^4, you apply the exponent to both the numerator and the denominator: 2434=1681\frac{2^4}{3^4} = \frac{16}{81}.
  • To simplify (pq)7\left(\frac{p}{q}\right)^7, you raise both the numerator and denominator to the 7th power, resulting in p7q7\frac{p^7}{q^7}.

Section 2

Reciprocal Property for Fractions with Exponent -1

Property

When a fraction is raised to the power of -1, it equals the reciprocal of the original fraction:

(ab)1=ba\left(\frac{a}{b}\right)^{-1} = \frac{b}{a}

Examples

Section 3

Negative Exponents for Fractions

Property

When a fraction has a negative exponent, flip the fraction and make the exponent positive:

(ab)n=(ba)n=bnan\left(\frac{a}{b}\right)^{-n} = \left(\frac{b}{a}\right)^n = \frac{b^n}{a^n}

Examples

Book overview

Jump across lessons in the current chapter without opening the full course modal.

Continue this chapter

Chapter 4: Fractions

  1. Lesson 1

    Lesson 1: What is a Fraction?

  2. Lesson 2

    Lesson 2: Multiplying Fractions

  3. Lesson 3

    Lesson 3: Dividing by a Fraction

  4. Lesson 4Current

    Lesson 4: Raising Fractions to Powers

  5. Lesson 5

    Lesson 5: Simplest Form of a Fraction

  6. Lesson 6

    Lesson 6: Comparing Fractions

  7. Lesson 7

    Lesson 7: Adding and Subtracting Fractions

  8. Lesson 8

    Lesson 8: Mixed Numbers