Sums & Products of Rational & Irrational Numbers Quick Check

1 answer

Certainly! Let's go over the sums and products of rational and irrational numbers. Here’s a quick reference guide:

Definitions

  • Rational Number: A number that can be expressed as the quotient of two integers (e.g., \( \frac{1}{2}, -3, 4.75 \)).
  • Irrational Number: A number that cannot be expressed as a simple fraction (e.g., \( \sqrt{2}, \pi, e \)).

Sums

  1. Rational + Rational:

    • Always rational.
    • Example: \( 2 + 3 = 5 \)
  2. Irrational + Irrational:

    • May be rational or irrational.
    • Example: \( \sqrt{2} + (-\sqrt{2}) = 0 \) (rational); \( \sqrt{2} + \sqrt{3} \) (irrational).
  3. Rational + Irrational:

    • Always irrational.
    • Example: \( 2 + \sqrt{3} \) is irrational.

Products

  1. Rational × Rational:

    • Always rational.
    • Example: \( 2 \times 3 = 6 \)
  2. Irrational × Irrational:

    • May be rational or irrational.
    • Example: \( \sqrt{2} \times \sqrt{2} = 2 \) (rational); \( \sqrt{2} \times \sqrt{3} \) (irrational).
  3. Rational × Irrational:

    • Always irrational (as long as the rational number is not zero).
    • Example: \( 2 \times \sqrt{3} \) is irrational.

Summary

  • Rational + Rational = Rational
  • Irrational + Irrational = May be Rational or Irrational
  • Rational + Irrational = Irrational
  • Rational × Rational = Rational
  • Irrational × Irrational = May be Rational or Irrational
  • Rational × Irrational = Irrational (if rational is non-zero)

If you need further examples or deeper explanation, feel free to ask!