If the domain of the function f(x) = frac1sqrt10 + 3x - x^2 + frac1sqrtx + |x| is (a, b), then (1 + a)^2 + b^2 is equal to:

Solution & Explanation

### Related Formula textFor frac1sqrtg(x) text to be defined, we require: g(x) > 0 ### Core Logic We find the domains of the two constituent terms separately and then find their intersection. ### Step 1: Find the domain of the first term For the first term to be defined: 10 + 3x - x^2 > 0 implies x^2 - 3x - 10 < 0 (x - 5)(x + 2) < 0 implies x in (-2, 5) quad text--- (1) ### Step 2: Find the domain of the second term For the second term to be defined: x + |x| > 0 - If x ge 0: x + x = 2x > 0 implies x > 0. - If x < 0: x - x = 0 ngtr 0. Thus, the domain of the second term is: x in (0, infty) quad text--- (2) ### Step 3: Find intersection and calculate the final expression Intersecting domains (1) and (2): x in (-2, 5) cap (0, infty) implies x in (0, 5) Comparing this with (a, b) gives a = 0 and b = 5. Now calculate the value: (1 + a)^2 + b^2 = (1 + 0)^2 + 5^2 = 1 + 25 = 26 ### Pattern Recognition Modulus domain constraint: The function x + |x| is non-zero only for positive values of x. This is a standard math trick that collapses complex domains down to x > 0 instantly. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Mathematics: Relations and Functions

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More Relations and Functions Previous-Year Questions — Page 3

Q54 jee_main_2025_29_jan_evening Domain of a Function
If the domain of the function log_5left(18x - x^2 -77 ight) is (alpha ,beta) and the domain of the function log_(x - 1)left(frac2x^2 + 3x - 2x^2 - 3x - 4right) is (gamma ,delta), then \alpha^2 +\beta^2 +\gamma^2 is equal to:
  • A. 174
  • B. 179
  • C. 186
  • D. 195

Solution

### Related Formula For a logarithmic term log_b(a) to be valid: a > 0, quad b > 0, quad b neq 1 ### Core Logic Analyzing the first function f_1(x) = log_5(18x - x^2 - 77): 18x - x^2 - 77 > 0 implies x^2 - 18x + 77 < 0 (x - 7)(x - 11) < 0 implies x in (7, 11) Hence, alpha = 7, beta = 11. ### Step 1: Check Second Function Base and Argument Analyzing f_2(x) = log_(x - 1)left(frac2x^2 + 3x - 2x^2 - 3x - 4right): Base constraints: x - 1 > 0 implies x > 1 x - 1 neq 1 implies x neq 2 Argument constraints: frac2x^2 + 3x - 2x^2 - 3x - 4 > 0 implies frac(2x - 1)(x + 2)(x - 4)(x + 1) > 0 ### Step 2: Apply Sign Scheme Using the wave-curve method to determine where the rational fraction is positive:
Domain of a Function diagram for Q54 - JEE Main 2025 Evening
Domain of a Function diagram for Q54 - JEE Main 2025 Evening
Combining this with x > 1 and x neq 2, the common interval is: x in (4, infty) Thus, gamma = 4. ### Step 3: Calculate final sum alpha^2 + beta^2 + gamma^2 = 7^2 + 11^2 + 4^2 = 49 + 121 + 16 = 186 ### Pattern Recognition For domain intersections involving variables in both the log base and argument, always list base rules (>0, neq 1) first to eliminate invalid sign fields early on. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Mathematics: Relations and Functions
Q54 jee_main_2025_28_jan_morning Functional Equations and Series
If f(x) = frac2^x2^x + sqrt2, x in mathbbR, then sum_k=1^81 fleft(frack82right) is equal to: (1) 41 (2) frac812 (3) 82 (4) 81sqrt2
  • A. 41
  • B. frac812
  • C. 82
  • D. 81sqrt2

Solution

### Related Formula Symmetric identity wrapper for matching indices: f(x) + f(1-x) = 1 ### Core Logic Let's evaluate f(x) + f(1-x): f(x) + f(1-x) = frac2^x2^x + sqrt2 + frac2^1-x2^1-x + sqrt2 = frac2^x2^x + sqrt2 + frac22 + sqrt2cdot 2^x = frac2^x + sqrt22^x + sqrt2 = 1 ### Step 1: Expanding the Series Pairing matching terms from opposite ends of the summation: sum_k=1^81 fleft(frack82right) = left[fleft(frac182right) + fleft(frac8182 ight)right] + dots + fleft(frac4182 ight) There are 40 complete pairs matching the f(x) + f(1-x) = 1 identity, plus one lone center term fleft(frac12right). ### Step 2: Computing Final Valuation textSum = 40 + fleft(frac12right) = 40 + fracsqrt2sqrt2 + sqrt2 = 40 + frac12 = frac812 ### Pattern Recognition When encountering fractional summation bounds, always check the sum of components x + (1-x) to find linear reduction templates. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Maths: Sequences and Series Class 12 Maths: Relations and Functions
Q55 jee_main_2025_28_jan_morning Functional Relations and Properties
Let f: mathbbR to mathbbR be a function defined by f(x) = (2 + 3a)x^2 + left( fraca + 2a - 1 right)x + b, a neq 1. If f(x + y) = f(x) + f(y) + 1 - frac27xy, then the value of 28sum_i = 1^5|f(i)| is: (1) 715 (2) 735 (3) 545 (4) 675
  • A. 715
  • B. 735
  • C. 545
  • D. 675

Solution

### Related Formula Given functional property equation: f(x + y) = f(x) + f(y) + 1 - frac27xy ### Core Logic Substitute x = y = 0 into the property equation: f(0) = 2f(0) + 1 implies f(0) = -1. Since f(0) = b, we instantly find b = -1. ### Step 1: Extracting Parameter Values Substitute y = -x into the property equation: f(0) = f(x) + f(-x) + 1 + frac27x^2 -1 = 2(3a + 2)x^2 + 2b + 1 + frac27x^2 Matching coefficients for x^2 gives: 6a + 4 + frac27 = 0 implies a = -frac57 Therefore, the absolute functional identity is: f(x) = -frac17x^2 - frac34x - 1 ### Step 2: Computing the Target Series Rewriting using common denominators: |f(x)| = frac128|4x^2 + 21x + 28| Evaluating for i=1 to 5: 28 sum_i = 1^5 |f(i)| = 675 ### Pattern Recognition Substituting standard points like 0 and -x decouples symmetric multi-variable systems with maximum efficiency. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Maths: Relations and Functions
Q57 jee_main_2025_28_jan_morning Equivalence Relations
The relation R = \(x, y) : x, y in mathbbZ 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 + x = 2x, which is always even. Thus, (x, x) in R. 2. **Symmetric:** If x + y is even, then y + x must also be even due to commutative addition. Thus, if (x, y) in R implies (y, x) in R. 3. **Transitive:** If x + y is even and y + z is even, then adding them gives (x + y) + (y + z) = x + 2y + z = texteven implies x + z = texteven - 2y = texteven. Thus, (x, z) in R. ### Step 1: Final Property Summary Since all three criteria are satisfies simultaneously, 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
Q55 jee_main_2025_03_april_morning Types of Relations
Let A = \-3, -2, -1, 0, 1, 2, 3\[cite: 555]. Let R be a relation on A defined by xRy if and only if 0 le x^2 + 2y le 4[cite: 555]. 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[cite: 556, 557]. Then l + m is equal to[cite: 558]:
  • A. 19
  • B. 20
  • C. 17
  • D. 18

Solution

### Related Formula 1. Elements in a relation satisfy the exact range constraint. 2. Reflexive criteria: For every x in A, (x, x) in R. ### Core Logic Rewrite the inequality to isolate variables systematically [cite: 1235]: -2y le x^2 le 4-2y [cite: 1235] Test every valid value of y in A to discover valid integer values for x[cite: 1237, 1238, 1241, 1259, 1260, 1261]: - 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 = -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 = 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 = 3 implies -6 le x^2 le -2 implies textNo real x text exists ### Step 1: Listing set elements and counting Compile all distinct matching coordinate pairs (x,y) into set 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)\ [cite: 1264] Counting elements gives [cite: 1265]: 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) must all belong to R. Checking missing elements [cite: 1267]: \(-1,-1), (2,2), (3,3)\ implies m = 3 [cite: 1267] Sum of variables [cite: 1268]: 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

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