Question

Which of the following is a null set :

• A. {0}
• B. {x : x > 0 or x < 0}
• C. {x : $x^2$ = 4 or x = 3}
• D. {x : $x^2$ + 1 = 0, x $\in$ R}

Answer 1

Answer: (D)

{x : $x^2$ + 1 = 0, x $\in$ R}

Answer 2

$x^2$ + 1 = 0 has no solution in R