The relation R on the set of real numbers defined by \(\mathrm{R} = \{(a, b): a \le b^2\}\) is
(A) Reflexive
(B) Not symmetric
(C) Neither reflexive nor transitive
(D) Transitive
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (B) and (C) only
Each property must hold for all real numbers, so one counterexample is enough to show that it fails.
R is reflexive only if \(a \le a^2\) for every real a. This fails for \(a = \frac{1}{2}\):
\(\displaystyle \left(\frac{1}{2}\right)^2 = \frac{1}{4} \lt \frac{1}{2}\)
R is symmetric only if \((a, b) \in R\) always gives \((b, a) \in R\). Take a = 1, b = 2:
\((1, 2) \in R\) since \(1 \le 2^2\)
\((2, 1) \notin R\) since \(2 \gt 1^2\)
R is transitive only if \((a, b) \in R\) and \((b, c) \in R\) always give \((a, c) \in R\). Take a = 5, b = 3, c = 2:
\((5, 3) \in R\) since \(5 \le 3^2\)
\((3, 2) \in R\) since \(3 \le 2^2\)
\((5, 2) \notin R\) since \(5 \gt 2^2\)
So R is not reflexive, not symmetric and not transitive.
Checking the statements
(A) Reflexive — Incorrect. \(\left(\frac{1}{2}, \frac{1}{2}\right) \notin R\), since \(\frac{1}{2} \gt \frac{1}{4}\).
(B) Not symmetric — Correct. \((1, 2) \in R\) but \((2, 1) \notin R\).
(C) Neither reflexive nor transitive — Correct. Both properties fail.
(D) Transitive — Incorrect. \((5, 3), (3, 2) \in R\) but \((5, 2) \notin R\).
NCERT (2026-27 edition):
Types of Relations
