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MATH 1150 · Radical expressions · Objective 1.3

Zero and Negative Rational Exponents

Interpret zero and negative rational exponents before combining rules.

CLO 1 · Topic 8 of 21
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Build the concept from the beginning

Meaning before procedure

For a ≠ 0, a⁰ = 1 and a^(−r) = 1/a^r. A negative exponent changes reciprocal position; it does not make the value negative.

Zero exponent
A nonzero base raised to zero equals 1.
Negative exponent
Signals a reciprocal.
Positive-exponent form
A final form with no negative exponents.
Nonzero restriction
A base moved to a denominator cannot be zero.

Interactive visual model

See how a negative rational exponent creates the reciprocal of a root–power value.

Change one control at a time and describe what changes—and what stays invariant.

A dependable four-step method

Identify zero and negative exponents.
Replace zero powers by 1.
Move negative powers across the fraction bar.
Apply rational-root meaning and state restrictions.
  1. Identify zero and negative exponents.
  2. Replace zero powers by 1.
  3. Move negative powers across the fraction bar.
  4. Apply rational-root meaning and state restrictions.
Three fully explained examples

Watch the reasoning, not just the answer

Example 1: Rewrite x^(−1/2) with a positive exponent.

Name the goalThe exponent is negative.
Choose the next moveMove the power to the denominator.
Carry out the mathematicsx^(−1/2) = 1/x^(1/2) = 1/√x.
Check and interpretMultiplying by x^(1/2) produces 1.

Example 2: Evaluate 16^(−3/4).

Name the goalUse the reciprocal of the positive power.
Choose the next moveEvaluate 16^(3/4) = 8.
Carry out the mathematics16^(−3/4) = 1/8.
Check and interpret8·1/8 = 1.

Example 3: Simplify a^(2/3)/a^(5/3).

Name the goalSubtract exponents.
Choose the next move2/3 − 5/3 = −1.
Carry out the mathematicsa^(−1) = 1/a, where a ≠ 0.
Check and interpret(1/a)·a^(5/3) = a^(2/3).
Interactive practice

Predict, decide, check, and revise

Interactive construction lab

Build a valid reasoning path

Choose the decisions in the order a careful solver would use them for this concept.

Choose this step, then check the construction.
Choose this step, then check the construction.
Choose this step, then check the construction.

The reasoning path changes as each decision is selected.

Readiness check

Check the foundation

For x ≠ 0, x⁰ equals what?

Rewrite x^(−1/2) with a positive exponent.

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Guided practice

Apply the method with support

Evaluate 9^(−1/2).

Evaluate 8^(−2/3).

Which statement is true?

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Independent practice

Work without step prompts

Simplify a^(1/2)/a^(3/2).

Rewrite 1/x^(−3/4).

Evaluate 16⁰ + 4^(1/2).

Why must a ≠ 0 in a^(−r)?

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Mastery check

Demonstrate durable understanding

Simplify x^(−2/3)x^(5/3).

Rewrite (ab)^(−1/2).

Evaluate 25^(−1).

Simplify y⁰/y^(−1/3).

Which final form uses only positive exponents?

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Unfamiliar transfer

Explain, compare, and revise

Rewrite (x^(−1/2)y⁰)/(z^(−2/3)) using only positive exponents.

Write a first attempt before opening the self-check.

The learner record reveals exact answers and model reasoning only after an attempt.