Math Problem Statement

Determine whether each number is rational or irrational.

Solution

Let's analyze each square root in the table to determine whether the resulting number is rational or irrational.

  1. √81:

    • √81 = 9. Since 9 is a whole number (an integer), this is a rational number.
  2. √15:

    • √15 is not a perfect square, and its square root is an infinite non-repeating decimal. Hence, this is an irrational number.
  3. -√101:

    • √101 is not a perfect square, and its square root is also an infinite non-repeating decimal. The negative sign does not change the fact that the square root is irrational. So, -√101 is irrational.
  4. -√36:

    • √36 = 6, which is a whole number. Therefore, -√36 = -6 is a rational number.

Final Answers:

  • √81: Rational
  • √15: Irrational
  • -√101: Irrational
  • -√36: Rational

Let me know if you'd like more details or have any questions!

Follow-up Questions:

  1. What makes a number rational versus irrational?
  2. Can a negative square root ever be irrational?
  3. Why is √101 irrational but √81 rational?
  4. How do you classify numbers that aren't square roots—are there other ways to tell if they're rational or irrational?
  5. What are some real-world applications of rational and irrational numbers?

Tip:

A rational number can always be expressed as a fraction of two integers, while an irrational number cannot—it has a decimal expansion that goes on forever without repeating.

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Math Problem Analysis

Mathematical Concepts

Square Roots
Rational Numbers
Irrational Numbers

Formulas

-

Theorems

Definition of Rational and Irrational Numbers

Suitable Grade Level

Grades 6-8