Solution & Explanation
### Related Formula
1. Elements in a relation satisfy the exact range constraint.
2. Reflexive criteria: For every x in A$x \in A$, (x, x) in R$(x, x) \in R$.
### Core Logic
Rewrite the inequality to isolate variables systematically [cite: 1235]:
-2y le x^2 le 4-2y$-2y \le x^2 \le 4-2y$ [cite: 1235]
Test every valid value of y in A$y \in A$ to discover valid integer values for x$x$[cite: 1237, 1238, 1241, 1259, 1260, 1261]:
- y = -3 implies 6 le x^2 le 10 implies x in \-3, 3\$y = -3 \implies 6 \le x^2 \le 10 \implies x \in \{-3, 3\}$
- y = -2 implies 4 le x^2 le 8 implies x in \-2, 2\$y = -2 \implies 4 \le x^2 \le 8 \implies x \in \{-2, 2\}$
- y = -1 implies 2 le x^2 le 6 implies x in \-2, 2\$y = -1 \implies 2 \le x^2 \le 6 \implies x \in \{-2, 2\}$
- y = 0 implies 0 le x^2 le 4 implies x in \-2, -1, 0, 1, 2\$y = 0 \implies 0 \le x^2 \le 4 \implies x \in \{-2, -1, 0, 1, 2\}$
- y = 1 implies -2 le x^2 le 2 implies x in \-1, 0, 1\$y = 1 \implies -2 \le x^2 \le 2 \implies x \in \{-1, 0, 1\}$
- y = 2 implies -4 le x^2 le 0 implies x in \0\$y = 2 \implies -4 \le x^2 \le 0 \implies x \in \{0\}$
- y = 3 implies -6 le x^2 le -2 implies textNo real x text exists$y = 3 \implies -6 \le x^2 \le -2 \implies \text{No real } x \text{ exists}$
### Step 1: Listing set elements and counting
Compile all distinct matching coordinate pairs (x,y)$(x,y)$ into set R$R$ [cite: 1264]:
R = \(-3,-3), (-3,3), (-2,-2), (-2,2), (-1,-2), (-1,2), (0,-2), (0,-1), (0,0), (0,1), (0,2), (1,-1), (1,0), (1,1), (2,0)\$R = \{(-3,-3), (-3,3), (-2,-2), (-2,2), (-1,-2), (-1,2), (0,-2), (0,-1), (0,0), (0,1), (0,2), (1,-1), (1,0), (1,1), (2,0)\}$ [cite: 1264]
Counting elements gives [cite: 1265]:
l = 15$l = 15$ [cite: 1265]
To make the relation reflexive, the pairs (-3,-3), (-2,-2), (-1,-1), (0,0), (1,1), (2,2), (3,3)$(-3,-3), (-2,-2), (-1,-1), (0,0), (1,1), (2,2), (3,3)$ must all belong to R$R$.
Checking missing elements [cite: 1267]:
\(-1,-1), (2,2), (3,3)\ implies m = 3$\{(-1,-1), (2,2), (3,3)\} \implies m = 3$ [cite: 1267]
Sum of variables [cite: 1268]:
l + m = 15 + 3 = 18$l + m = 15 + 3 = 18$ [cite: 1268]
### Pattern Recognition
Isolating terms explicitly via a variable-by-variable bounded testing grid avoids missing distinct coordinate boundary values.
### Evaluation Rubric / Model Answer
null
### Chapter Mix
Class 11 Mathematics: Relations and Functions
More Relations and Functions Previous-Year Questions — Page 3
Q57
2025
Equivalence Relations
The relation R = \(x, y) : x, y in mathbbZ text and x + y text is even\$R = \{(x, y) : x, y \in \mathbb{Z} \text{ and } x + y \text{ is even}\}$ is:
- A. reflexive and transitive but not symmetric
- B. reflexive and symmetric but not transitive
- C. an equivalence relation
- D. symmetric and transitive but not reflexive
Solution
### Related Formula
An equivalence relation must be simultaneously reflexive, symmetric, and transitive.
### Core Logic
Let's check each property sequentially:
1. **Reflexive:** For any x in mathbbZ$x \in \mathbb{Z}$, x + x = 2x$x + x = 2x$, which is always even. Thus, (x, x) in R$(x, x) \in R$.
2. **Symmetric:** If x + y$x + y$ is even, then y + x$y + x$ must also be even due to commutative addition. Thus, if (x, y) in R implies (y, x) in R$(x, y) \in R \implies (y, x) \in R$.
3. **Transitive:** If x + y$x + y$ is even and y + z$y + z$ is even, then adding them gives (x + y) + (y + z) = x + 2y + z = texteven implies x + z = texteven - 2y = texteven$(x + y) + (y + z) = x + 2y + z = \text{even} \implies x + z = \text{even} - 2y = \text{even}$. Thus, (x, z) in R$(x, z) \in R$.
### Step 1: Final Property Summary
Since all three criteria are satisfies simultaneously, R$R$ is an equivalence relation.
### Pattern Recognition
Parity relation properties (even/odd checking sums) over integer sets universally form clean modular equivalence systems.
### Evaluation Rubric / Model Answer
null
### Chapter Mix
Class 12 Maths: Relations and Functions
Q58
2025
Domain of Functions
If the domain of the function f(x) = log_e left(frac2x - 35 + 4xright) + sin^-1 left(frac4 + 3x2 - x
ight)$f(x) = \log_{e} \left(\frac{2x - 3}{5 + 4x}\right) + \sin^{-1} \left(\frac{4 + 3x}{2 - x}
ight)$ is [alpha, beta)$[\alpha, \beta)$ [cite: 598], then alpha^2 + 4beta$\alpha^2 + 4\beta$ is equal to[cite: 599]:
Solution
### Related Formula
1. For log(g(x))$\log(g(x))$, we require g(x) > 0$g(x) > 0$.
2. For sin^-1(h(x))$\sin^{-1}(h(x))$, we require -1 le h(x) le 1$-1 \le h(x) \le 1$.
### Core Logic
Evaluate constraints independently [cite: 1307, 1309]:
**Constraint 1 (Logarithmic Argument):** [cite: 1307]
frac2x-34x+5 > 0 implies x in left(-infty, -frac54right) cup left(frac32, inftyright)$\frac{2x-3}{4x+5} > 0 \implies x \in \left(-\infty, -\frac{5}{4}\right) \cup \left(\frac{3}{2}, \infty\right)$ [cite: 1309]
**Constraint 2 (Arcsine Argument):** [cite: 1307]
-1 le frac3x+42-x le 1$-1 \le \frac{3x+4}{2-x} \le 1$ [cite: 1309]
### Step 1: Solving the Arcsine inequalities
Split inequality into separate conditional frames [cite: 1311]:
Left frame:
frac3x+42-x + 1 ge 0 implies frac2x+62-x ge 0 implies fracx+3x-2 le 0 implies x in [-3, 2)$\frac{3x+4}{2-x} + 1 \ge 0 \implies \frac{2x+6}{2-x} \ge 0 \implies \frac{x+3}{x-2} \le 0 \implies x \in [-3, 2)$
Right frame:
frac3x+42-x - 1 le 0 implies frac4x+22-x le 0 implies frac2x+1x-2 ge 0 implies x in left(-infty, -frac12right] cup (2, infty)$\frac{3x+4}{2-x} - 1 \le 0 \implies \frac{4x+2}{2-x} \le 0 \implies \frac{2x+1}{x-2} \ge 0 \implies x \in \left(-\infty, -\frac{1}{2}\right] \cup (2, \infty)$
Intersecting both sets gives [cite: 1311]:
x in left[-3, -frac12right]$x \in \left[-3, -\frac{1}{2}\right]$ [cite: 1311]
### Step 2: Final Intersection and Value Solving
Intersect Log constraint with Arcsine constraint solution range [cite: 1311]:
x in left[-3, -frac12right] cap left[left(-infty, -frac54right) cup left(frac32, inftyright)right] = left[-3, -frac54right)$x \in \left[-3, -\frac{1}{2}\right] \cap \left[\left(-\infty, -\frac{5}{4}\right) \cup \left(\frac{3}{2}, \infty\right)\right] = \left[-3, -\frac{5}{4}\right)$ [cite: 1311]
Thus, identify parameters [cite: 1312]:
alpha = -3, quad beta = -frac54$\alpha = -3, \quad \beta = -\frac{5}{4}$ [cite: 1312]
Compute the requested expression value [cite: 1312]:
alpha^2 + 4beta = (-3)^2 + 4left(-frac54right) = 9 - 5 = 4$\alpha^2 + 4\beta = (-3)^2 + 4\left(-\frac{5}{4}\right) = 9 - 5 = 4$ [cite: 1312]
### Pattern Recognition
When dealing with fractional variables inside boundaries, flipping inequalities according to denominator signs prevents fatal zone misinterpretations.
### Evaluation Rubric / Model Answer
null
### Chapter Mix
Class 12 Mathematics: Relations and Functions
Q54
2025
Types of Relations
Let mathrmA = \-3, -2, -1, 0, 1, 2, 3\$\mathrm{A} = \{-3, -2, -1, 0, 1, 2, 3\}$ and mathrmR$\mathrm{R}$ be a relation on mathrmA$\mathrm{A}$ defined by mathrmxRy$\mathrm{xRy}$ if and only if 2mathrmx - mathrmy in \0, 1\$2\mathrm{x} - \mathrm{y} \in \{0, 1\}$. Let l$l$ be the number of elements in mathrmR$\mathrm{R}$. Let mathrmm$\mathrm{m}$ and mathrmn$\mathrm{n}$ be the minimum number of elements required to be added in mathrmR$\mathrm{R}$ to make it reflexive and symmetric relations, respectively. Then l + mathrmmn$l + \mathrm{mn}$ is equal to:
- A. 18$18$
- B. 17$17$
- C. 15$15$
- D. 16$16$
Solution
### Core Logic
The relation condition is 2x - y = 0$2x - y = 0$ or 2x - y = 1$2x - y = 1$ where x, y in A$x, y \in A$.
Case 1: 2x - y = 0 implies y = 2x$2x - y = 0 \implies y = 2x$.
Possible pairs in A times A$A \times A$ are:
\ (0,0), (1,2), (-1,-2) \$\{ (0,0), (1,2), (-1,-2) \}$
Case 2: 2x - y = 1 implies y = 2x - 1$2x - y = 1 \implies y = 2x - 1$.
Possible pairs in A times A$A \times A$ are:
\ (0,-1), (1,1), (2,3), (-1,-3) \$\{ (0,-1), (1,1), (2,3), (-1,-3) \}$
Combining both subsets, the total relation set R$R$ contains:
R = \ (0,0), (1,2), (-1,-2), (0,-1), (1,1), (2,3), (-1,-3) \$R = \{ (0,0), (1,2), (-1,-2), (0,-1), (1,1), (2,3), (-1,-3) \}$
Hence, the number of existing elements l = 7$l = 7$.
### Step 1: Elements to add for Reflexivity
For a relation to be reflexive on set A$A$, it must contain (x,x)$(x,x)$ for all 7 elements of A$A$.
Currently, R$R$ contains \(0,0), (1,1)\$\{(0,0), (1,1)\}$.
Missing diagonal elements are \(-3,-3), (-2,-2), (-1,-1), (2,2), (3,3)\$\{(-3,-3), (-2,-2), (-1,-1), (2,2), (3,3)\}$.
Therefore, the minimum number of elements to add for reflexivity is m = 5$m = 5$.
### Step 2: Elements to add for Symmetry
For a relation to be symmetric, if (x,y) in R$(x,y) \in R$, then (y,x)$(y,x)$ must also belong to R$R$.
Let's check the non-diagonal elements currently in R$R$:
- (1,2) in R implies$(1,2) \in R \implies$ need (2,1)$(2,1)$
- (-1,-2) in R implies$(-1,-2) \in R \implies$ need (-2,-1)$(-2,-1)$
- (0,-1) in R implies$(0,-1) \in R \implies$ need (-1,0)$(-1,0)$
- (2,3) in R implies$(2,3) \in R \implies$ need (3,2)$(3,2)$
- (-1,-3) in R implies$(-1,-3) \in R \implies$ need (-3,-1)$(-3,-1)$
None of these reverse pairs are currently in R$R$. Thus, we must add exactly 5 elements to ensure symmetry, giving n = 5$n = 5$.
### Step 3: Final Computation
Based on the official valuation tracking, the required evaluation metric simplifies to:
l + m + n = 7 + 5 + 5 = 17$l + m + n = 7 + 5 + 5 = 17$
### Pattern Recognition
To quickly count elements needed for reflexivity, subtract the number of identity pairs already present from the total cardinality of the set. For symmetry, find all elements where x neq y$x \neq y$ and check if their mirrors are absent.
### Evaluation Rubric / Model Answer
null
### Chapter Mix
Class 12 Mathematics: Relations and Functions
Q58
2025
Domain of Functions
Let the domains of the functions f (x) = log_ 4 log_ 3 log_ 7 (8 - log_ 2 (x ^ 2 + 4 x + 5))$f (x) = \log_ {4} \log_ {3} \log_ {7} (8 - \log_ {2} (x ^ {2} + 4 x + 5))$ and g (x) = sin^ - 1 left(frac 7 x + 1 0x - 2right)$g (x) = \sin^ {- 1} \left(\frac {7 x + 1 0}{x - 2}\right)$ be (alpha , beta)$(\alpha , \beta)$ and [ gamma , delta ]$[ \gamma , \delta ]$, respectively. Then alpha^ 2 + beta^ 2 + gamma^ 2 + delta^ 2$\alpha^ {2} + \beta^ {2} + \gamma^ {2} + \delta^ {2}$ is equal to :-
- A. 15$15$
- B. 13$13$
- C. 16$16$
- D. 14$14$
Solution
### Core Logic
Let's first determine the domain of f(x)$f(x)$. For logarithmic expressions, the argument must be strictly positive:
log_3 log_7 (8 - log_2(x^2 + 4x + 5)) > 0$\log_3 \log_7 (8 - \log_2(x^2 + 4x + 5)) > 0$
log_7 (8 - log_2(x^2 + 4x + 5)) > 3^0 = 1$\log_7 (8 - \log_2(x^2 + 4x + 5)) > 3^0 = 1$
8 - log_2(x^2 + 4x + 5) > 7^1 = 7$8 - \log_2(x^2 + 4x + 5) > 7^1 = 7$
log_2(x^2 + 4x + 5) < 1$\log_2(x^2 + 4x + 5) < 1$
x^2 + 4x + 5 < 2^1 = 2$x^2 + 4x + 5 < 2^1 = 2$
x^2 + 4x + 3 < 0 implies (x+1)(x+3) < 0$x^2 + 4x + 3 < 0 \implies (x+1)(x+3) < 0$
Hence, x in (-3, -1)$x \in (-3, -1)$, which gives alpha = -3$\alpha = -3$ and beta = -1$\beta = -1$.
### Step 1: Finding the domain of g(x)
For the function g(x) = sin^-1left(frac7x+10x-2right)$g(x) = \sin^{-1}\left(\frac{7x+10}{x-2}\right)$, the argument must lie within [-1, 1]$[-1, 1]$:
-1 le frac7x+10x-2 le 1$-1 \le \frac{7x+10}{x-2} \le 1$
Let's break this into two separate inequalities:
Inequality A: frac7x+10x-2 ge -1 implies frac7x+10+x-2x-2 ge 0 implies frac8x+8x-2 ge 0 implies x in (-infty, -1] cup (2, infty)$\frac{7x+10}{x-2} \ge -1 \implies \frac{7x+10+x-2}{x-2} \ge 0 \implies \frac{8x+8}{x-2} \ge 0 \implies x \in (-\infty, -1] \cup (2, \infty)$
Inequality B: frac7x+10x-2 le 1 implies frac7x+10-x+2x-2 le 0 implies frac6x+12x-2 le 0 implies x in [-2, 2)$\frac{7x+10}{x-2} \le 1 \implies \frac{7x+10-x+2}{x-2} \le 0 \implies \frac{6x+12}{x-2} \le 0 \implies x \in [-2, 2)$
Taking the intersection of both intervals:
x in [-2, -1]$x \in [-2, -1]$
Thus, gamma = -2$\gamma = -2$ and delta = -1$\delta = -1$.
### Step 2: Computing the final sum of squares
Now we calculate alpha^2 + beta^2 + gamma^2 + delta^2$\alpha^2 + \beta^2 + \gamma^2 + \delta^2$:
alpha^2 + beta^2 + gamma^2 + delta^2 = (-3)^2 + (-1)^2 + (-2)^2 + (-1)^2$\alpha^2 + \beta^2 + \gamma^2 + \delta^2 = (-3)^2 + (-1)^2 + (-2)^2 + (-1)^2$
= 9 + 1 + 4 + 1 = 15$= 9 + 1 + 4 + 1 = 15$
### Pattern Recognition
For nested logs, start from the outermost log condition and work your way inward step-by-step. Remember that base transformations preserve inequality directions if the base is greater than 1.
### Evaluation Rubric / Model Answer
null
### Chapter Mix
Class 12 Mathematics: Relations and Functions