Easy MCQ +4 / -1 PYQ · JEE Mains 2020

If R = {(x, y) : x, y $\in$ Z, x2 + 3y2 $\le$ 8} is a relation on the set of integers Z, then the domain of R–1 is :

  1. A {0, 1}
  2. B {–2, –1, 1, 2}
  3. C {–1, 0, 1} Correct answer
  4. D {–2, –1, 0, 1, 2}

Solution

Given R = {(x, y) : x, y $\in$ Z, x<sup>2</sup> + 3y<sup>2</sup> $\le$ 8} <br><br>So R = {(0,1), (0,–1), (1,0), (–1,0), (1,1), (1,-1) <br>(-1,1), (-1,-1), (2,0), (-2,0), (-2,0), (2,1), (2,-1), (-2,1), (-2,-1)} <br><br>$\Rightarrow$ R : { -2, -1, 0, 1, 2} $\to$ {-1, 0, 1} <br><br>$\therefore$ R<sup>-1</sup> : {-1, 0, 1} $\to$ { -2, -1, 0, 1, 2} <br><br>$\therefore$ Domain of R<sup>–1</sup> = {-1, 0, 1}

About this question

Subject: Mathematics · Chapter: Sets, Relations and Functions · Topic: Sets and Operations

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