Real Numbers

The complete set of numbers that can be represented on the number line.

Introduction

The collection of all Rational Numbers and Irrational Numbers together forms the set of Real Numbers.

Definition and Notation

The set of Real Numbers is denoted by R.
R = Q (Rational) ∪ T (Irrational)

The Real Number Line

Every real number is represented by a unique point on the number line. Also, every point on the number line represents a unique real number.

Laws of Exponents for Real Numbers

For a > 0 being a real number and p, q being rational numbers:

  • ap × aq = ap+q (Product Law)
  • (ap)q = apq (Power of a Power)
  • ap / aq = ap-q (Quotient Law)
  • ap × bp = (ab)p (Power of a Product)
  • a0 = 1
  • a-n = 1 / an

Rationalization

If the denominator of an expression contains a square root (making it irrational), we convert it into an equivalent expression with a rational denominator.
Example: 1/√2 = √2/2.
To rationalize 1/(a+√b), multiply numerator and denominator by (a-√b).

Practice Questions

Free Preview - 10 Questions

Test your understanding of Real Numbers.

1 The set of Real Numbers consists of:
  • A Only Rational Numbers
  • B Only Irrational Numbers
  • C Both Rational and Irrational Numbers
  • D Only Integers
Explanation:
Real numbers are the union of the set of rational numbers and the set of irrational numbers.
2 Simplify: 2⁵ × 2⁻³
  • A 2⁸
  • B 4
  • C 2⁻¹⁵
  • D 1/4
Explanation:
Using ap × aq = ap+q: 25+(-3) = 22 = 4.
3 Every real number corresponds to:
  • A A unique point on the number line
  • B Two points on the number line
  • C Only positive points
  • D Only integer points
Explanation:
This is a fundamental property of the real number line. There is a one-to-one correspondence between real numbers and points on the line.
4 (64)1/2 is equal to:
  • A 4
  • B 8
  • C 32
  • D 16
Explanation:
The exponent 1/2 represents the square root. √64 = 8. (Since 8² = 64).
5 Which is true?
  • A Every real number is irrational
  • B Every real number is rational
  • C Every irrational number is a real number
  • D Every real number is an integer
Explanation:
The set of real numbers contains all irrational numbers. Therefore, every irrational number belongs to the set of real numbers.
6 Rationalize the denominator of 1 / (√3 - √2).
  • A √3 - √2
  • B √3 + √2
  • C 1
  • D √5
Explanation:
Multiply numerator and denominator by (√3 + √2). Denominator becomes (√3)² - (√2)² = 3 - 2 = 1. Result: √3 + √2.
7 Value of (32)1/5 is:
  • A 2
  • B 4
  • C 8
  • D 1
Explanation:
32 = 2⁵. So (2⁵)1/5 = 2(5 × 1/5) = 2¹ = 2.
8 If x = 2 and y = 3, then xy + yx = ?
  • A 13
  • B 17
  • C 36
  • D 6
Explanation:
2³ + 3² = 8 + 9 = 17.
9 Identify the Real Number from the list:
  • A √-1
  • B 1/0
  • C -√5
  • D None of the above
Explanation:
√-1 is imaginary. 1/0 is undefined. -√5 is an irrational number, which implies it is a real number.
10 The value of 71/2 × 81/2 is:
  • A 56
  • B (56)1/2
  • C 151/2
  • D (56)2
Explanation:
Using ap × bp = (ab)p: 71/2 × 81/2 = (7×8)1/2 = 561/2 = √56.

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