Questions and Solutions
Question 1:
Let A = {0, 1, 2, 3, 4, 5}. Let R be a relation on A defined by (x, y) ∈ R if and only if max{x, y} ∈ {3, 4}. Then among the statements (S1): The number of elements in R is 18, and (S2): The relation R is symmetric but neither reflexive nor transitive
Question 2:
Let \[ A = \{(\alpha, \beta) \in \mathbb{R} \times \mathbb{R} : |\alpha - 1| \leq 4 \;\;\text{and}\;\; |\beta - 5| \leq 6\} \] and \[ B = \{(\alpha, \beta) \in \mathbb{R} \times \mathbb{R} : 16(\alpha - 2)^2 + 9(\beta - 6)^2 \leq 144\}. \]
Question 3:
Let \[ A = \{-3, -2, -1, 0, 1, 2, 3\} \] and \(R\) be a relation on \(A\) defined by \[ x R y \;\;\text{if and only if}\;\; 2x - y \in \{0,1\}. \] Let \(l\) be the number of elements in \(R\). Let \(m\) and \(n\) be the minimum number of elements required to be added in \(R\) to make it reflexive and symmetric relations, respectively. Then \(l+m+n\) is equal to:
Question 4:
Consider the sets \[ A = \{(x, y) \in \mathbb{R} \times \mathbb{R} : x^2 + y^2 = 25\}, \quad B = \{(x, y) \in \mathbb{R} \times \mathbb{R} : x^2 + 9y^2 = 144\}, \] \[ C = \{(x, y) \in \mathbb{Z} \times \mathbb{Z} : x^2 + y^2 \leq 4\}, \quad D = A \cap B. \] The total number of one-one functions from the set \(D\) to the set \(C\) is:
Question 5:
Let \(A = \{-2,-1,0,1,2,3\}\). Let \(R\) be a relation on \(A\) defined by \[ x \,R\, y \iff y = \max\{x,1\}. \] Let \(l\) be the number of elements in \(R\). Let \(m\) and \(n\) be the minimum number of elements required to be added in \(R\) to make it reflexive and symmetric relations, respectively. Then \(l+m+n\) is equal to:
Question 6:
Let \(A = \{-3,-2,-1,0,1,2,3\}\). Let \(R\) be a relation on \(A\) defined by \[ x \,R\, y \iff 0 \leq x^2 + 2y \leq 4. \] Let \(l\) be the number of elements in \(R\) and \(m\) be the minimum number of elements required to be added in \(R\) to make it a reflexive relation. Then \(l+m\) is equal to:
Question 7:
Let \(A=\{1,2,3, \ldots ., 100\}\) and \(R\) be a relation on \(A\) such that \(R=\{(a, b): a=2 b+1\}\). Let \((a_1,\,a_2),(a_2,\,a_3),(a_3,\,a_4), \ldots .,(a_k,\,a_{k+1})\) be a sequence of \(k\) elements of \(R\) such that the second entry of an ordered pair is equal to the first entry of the next ordered pair. Then the largest integer \(k\) , for which such a sequence exists, is equal to :