Which of the following is the empty set - Vidyadip

MCQ

Which of the following is the empty set

A
$\{ x:x$ is a real number and ${x^2} - 1 = 0\} $
✓
$\{ x:x$ is a real number and ${x^2} + 1 = 0\} $
C
$\{ x:x$ is a real number and ${x^2} - 9 = 0\} $
D
$\{ x:x$ is a real number and ${x^2} = x + 2\} $

✓

Answer

Correct option: B.

$\{ x:x$ is a real number and ${x^2} + 1 = 0\} $

b
(b) Since ${x^2} + 1 = 0,$ gives ${x^2} = - 1$

$ \Rightarrow $ $x = \pm$ $ i x$ is not real but $x$ is real (given) No value of $x$ is possible.

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