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← JEE Main 2026 · 8 Apr · Shift 2
MathematicsSingle correct+4 / -1Question 1 of 75

JEE Main 2026 · 8 Apr · Shift 2, Mathematics question 1

Consider the relation R on the set {−2,−1,0,1,2}\{-2,-1,0,1,2\} defined by (a,b)∈R(a,b)\in R if and only if 1+ab>01+ab>0. Then, among the statements :

I. The number of elements in R is 17

II. R is an equivalence relation

Choose one option
Answer and worked solution

Official answer: A

Count. Of the 25 pairs, 1+ab≤01+ab\le0 only when a and b are non-zero with opposite signs: a∈{−2,−1}a\in\{-2,-1\}, b∈{1,2}b\in\{1,2\} or the reverse, 8 pairs. So R has 17 elements: I is true.

Equivalence? R is reflexive (1+a2>01+a^2>0) and symmetric, but not transitive: (2,0),(0,−2)∈R(2,0),(0,-2)\in R while 1+2(−2)<01+2(-2)<0. II is false.

(A)

Topics:Relations