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Rational Exponent

Rational Exponent

One-page printable reference

See It in Action

Two examples of the idea done right—and one common look-alike that is not right.

EXAMPLE

EXAMPLE

NON-EXAMPLE

Definition

A rational exponent is an exponent that is a fraction (or rational number). In other words, a rational exponent represents a power and a root simultaneously.

Definition:

A rational exponent is an exponent that can be written as a fraction, i.e., m/n, where m and n are integers, and n does not equal 0. The rational exponent a^m/n means the n-th root of a raised to the power of m, or equivalently, it can be written as:


A to the m over n power equals the nth root of a all to the m power equals the nth root of a to the m power.

Key Concepts:

  • Numerator (m): This represents the power to which the number a is raised.

  • Denominator (n): This represents the root of the number a.

Examples of Rational Exponents:

1. Square root as a rational exponent:

   

The square root of a equals a to the one half power.

   

   



The square root of a is the same as raising a to the power of 1/2.


2. Cube root as a rational exponent:

   

The cube root of a equals a to the one third power.

   

   



The cube root of a is the same as raising a to the power of 1/3.


3. Raising a number to a rational exponent:

   

Eight to the two thirds power equals the cube root of eight all squared equals two squared equals four.

   



Here, 8^2/3 means first taking the cube root of 8 (which is 2), and then squaring it (which gives 4).

Rules for Rational Exponents:

You can apply the same exponent rules for rational exponents as you do for integer exponents:

Product of Powers: a to the m over n power times a to the p over n power equals a to the m plus p over n power.


Power of a Power: a to the m over n power all raised to the k power equals a to the m times k over n power.



Quotient of Powers: a to the m over n power all over a to the p over n power equals a to the m minus p over n power.




Conclusion:

A rational exponent is a way to express both roots and powers using exponents in fractional form. By using rational exponents, you can express roots (like square roots or cube roots) and powers in a unified and algebraically consistent way.

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