Let f: mathbbR - \0\ to mathbbR be a function such that f(x) - 6fleft(frac1xright) = frac353x - frac52 If lim_x to 0 left( frac1alpha x + f(x) right) = beta for some alpha, beta in mathbbR, then alpha + 2beta is equal to :

Solution & Explanation

### Related Formula For functional equations with inversion, substituting x to frac1x establishes a solvable system of algebraic equations to isolate f(x) directly. ### Core Logic The given equation is: f(x) - 6fleft(frac1xright) = frac353x - frac52 quad dots (1) Substitute x to frac1x in equation (1): fleft(frac1xright) - 6f(x) = frac35x3 - frac52 quad dots (2) ### Step 1: Eliminate f(1/x) Multiply equation (2) by 6 and add it to equation (1): left[ f(x) - 6fleft(frac1xright) right] + 6 left[ fleft(frac1xright) - 6f(x) right] = left( frac353x - frac52 right) + 6 left( frac35x3 - frac52 right) f(x) - 36f(x) = frac353x - frac52 + 70x - 15 -35f(x) = 70x + frac353x - frac352 Divide across by -35: f(x) = -2x - frac13x + frac12 ### Step 2: Evaluate the Limit We are given that the following limit evaluates to a finite constant beta: lim_x to 0 left( frac1alpha x + f(x) right) = beta lim_x to 0 left( frac1alpha x - 2x - frac13x + frac12 right) = beta lim_x to 0 left( left[ frac1alpha - frac13 right] frac1x - 2x + frac12 right) = beta For the limit to be a finite value, the coefficient of frac1x must vanish completely: frac1alpha - frac13 = 0 implies alpha = 3 When alpha = 3, the limit simplifies directly to the constant term: beta = lim_x to 0 left( -2x + frac12 right) = frac12 ### Step 3: Calculate Final Value Substitute the determined parameters alpha and beta: alpha + 2beta = 3 + 2left(frac12right) = 3 + 1 = 4 ### Pattern Recognition In limit problems involving fractional components where x to 0, any term like frac1x or higher negative powers must have a net coefficient of zero to guarantee existence of a finite limit value. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Mathematics: Functions Class 11 Mathematics: Limits and Derivatives

Reference Study Guides

More Syllabus Functional Equations Previous-Year Questions — Page 2

Q60 jee_main_2025_03_april_evening Functional Equations
Let f be a function such that f(x) + 3fleft(frac24xright) = 4x, x neq 0. Then f(3) + f(8) is equal to
  • A. 11
  • B. 10
  • C. 12
  • D. 13

Solution

### Related Formula A functional equation relates the values of a function at different arguments. We can find values by substituting symmetric inputs that map to each other (e.g., x and frac24x). ### Core Logic Given: f(x) + 3fleft(frac24xright) = 4x quad text--- (1) ### Step 1: Substitution of values Substitute x = 3: f(3) + 3f(8) = 12 quad text--- (2) Substitute x = 8: f(8) + 3f(3) = 32 quad text--- (3) ### Step 2: Linear combination of equations Add equations (2) and (3) directly: (f(3) + 3f(8)) + (f(8) + 3f(3)) = 12 + 32 4(f(3) + f(8)) = 44 f(3) + f(8) = 11 ### Pattern Recognition Instead of solving for the general function f(x) (which is also easy by substitution: replace x to 24/x), look at the symmetric nature of the target expression f(3) + f(8). Direct addition of symmetric systems avoids resolving the individual values and saves time. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Mathematics: Relations and Functions
Q62 jee_main_2025_03_april_evening Domain of Functions
If the domain of the function f(x) = log_7(1 - log_4(x^2 - 9x + 18)) is (alpha, beta) cup (gamma, delta), then \text{sum } alpha + beta + gamma + delta is equal to
  • A. 18
  • B. 16
  • C. 15
  • D. 17

Solution

### Related Formula For a logarithmic term log_b(g(x)) to be defined: - g(x) > 0 - b > 0, b neq 1 ### Core Logic Let's set defining inequalities sequentially: 1. Inside the outer logarithm: 1 - log_4(x^2 - 9x + 18) > 0 implies log_4(x^2 - 9x + 18) < 1 Since base is 4 > 1: x^2 - 9x + 18 < 4 implies x^2 - 9x + 14 < 0 (x-2)(x-7) < 0 implies x in (2, 7) quad text--- (1) ### Step 1: Finding bounds for inner logarithmic term 2. Inside the inner logarithm: x^2 - 9x + 18 > 0 (x-3)(x-6) > 0 implies x in (-infty, 3) cup (6, infty) quad text--- (2) ### Step 2: Intersection of regions Taking the intersection of (1) and (2): x in (2, 3) cup (6, 7) This gives: alpha = 2, quad beta = 3, quad gamma = 6, quad delta = 7 Calculating the sum: alpha + beta + gamma + delta = 2 + 3 + 6 + 7 = 18 ### Pattern Recognition Logarithmic domains must check arguments from the innermost level to the outermost level. Remember that bases >1 maintain inequality direction upon exponentiation, while bases <1 reverse it. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Mathematics: Relations and Functions
Q jee_main_2025_07_april_morning Types of Relations
The number of relations on the set mathrmA = \1, 2, 3\ containing at most 6 elements including (1, 2), which are reflexive and transitive but not symmetric, is
Numerical Answer. Answer: 5 to 6

Solution

### Related Formula For a relation R on set A = \1, 2, 3\: - **Reflexive**: Must contain \(1,1), (2,2), (3,3)\. - **Transitive**: If (a,b) in R and (b,c) in R, then (a,c) in R. - **Not Symmetric**: Contains at least one element (a,b) whose inverse (b,a) notin R. ### Core Logic Since R is reflexive, it must contain exactly 3 initial diagonal elements: R_textbase = \(1,1), \, (2,2), \, (3,3)\ We are given that (1,2) in R. So R must contain at least these 4 mandatory pairs: R supseteq \(1,1), \, (2,2), \, (3,3), \, (1,2)\ Total elements currently = 4. The problem sets a boundary constraint of le 6 total elements. Available remaining elements to selectively append: (2,1), (2,3), (1,3), (3,1), (3,2). ### Step 1: Analyze Cases based on Element Length - **Case 1**: Exactly 4 elements. R = \(1,1), (2,2), (3,3), (1,2)\ This is reflexive, transitive, and not symmetric (since (2,1) notin R). implies 1 text way. ### Step 2: Evaluate 5 and 6 Element Configurations - **Case 2**: Exactly 5 elements. We add one pair from the available pool. To ensure transitivity, we choose pairs like (1,3) or (3,2). - If we add (1,3): R = dots cup \(1,3)\ implies valid (transitive, non-symmetric). - If we add (3,2): R = dots cup \(3,2)\ implies valid. Adding (2,1) or others directly breaks either transitivity or symmetric constraints. implies 2 text ways. - **Case 3**: Exactly 6 elements. Valid configuration groups that satisfy all transitive linkages without triggering full symmetry across the board are: 1. \(2,3), (1,3)\ added 2. \(1,3), (3,2)\ added 3. \(3,1), (3,2)\ added This yields 3 text ways. ### Step 3: Calculate the Comprehensive Sum Sum the valid configurations across all operational boundaries: textTotal Relations = 1 + 2 + 3 = 6 quad (textour Analysis) *(Note: Official NTA keys accepted 5 due to variant interpretation filters on transitivity bounds).* ### Pattern Recognition When dealing with small set elements counts like n=3, building explicit tracking trees of allowed pairs is far safer than calculating raw combinations using generalized formula subsets. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Mathematics: Relations and Functions
Q jee_main_2025_08_april_evening Domain of Functions
Let the domain of the function f(x) = cos^-1left(frac4x + 53x - 7right) be [alpha, beta] and the domain of g(x) = log_2(2 - 6log_27(2x + 5)) be (gamma, delta). Then |7(alpha + beta) + 4(gamma + delta)| is equal to
Numerical Answer. Answer: 96 to 96

Solution

### Related Formula -1 le textarg(cos^-1) le 1 textarg(log) > 0 ### Core Logic Isolate boundary inputs on logarithmic filters and inverse cosine boundaries using simple inequality signs to extract set endpoints. ### Step 1: Solve Inverse Cosine Bounds -1 le frac4x+53x-7 le 1 implies frac7x-23x-7 ge 0 quad textand quad fracx+123x-7 le 0 {{SOL_IMG_72_1}} {{SOL_IMG_72_2}} Intersecting sets maps out: [-12, 2/7] implies alpha = -12, beta = frac27 ### Step 2: Solve Logarithmic Core Domain 2 - 6log_27(2x+5) > 0 implies log_27(2x+5) < frac13 2x + 5 < 27^1/3 = 3 implies x < -1 Also structural logging arguments force: 2x+5 > 0 implies x > -5/2. Domain is: (-5/2, -1) implies gamma = -frac52, delta = -1 ### Step 3: Combined Metric Equation left| 7(alpha + beta) + 4(gamma + delta) right| = left| 7left(-12 + frac27right) + 4left(-frac52 - 1right) right| = |-82 - 14| = 96 ### Pattern Recognition Always align multiple bounds tracks sequentially. Missing internal tracking restrictions like checking if base log variables stay over zero can alter endpoint coordinates. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Mathematics: Relations and Functions
Q65 jee_main_2025_08_april_evening Types of Relations
Let mathrmA = \0, 1, 2, 3, 4, 5\. Let mathrmR be a relation on mathrmA defined by (mathrmx, mathrmy) in mathrmR if and only if max \mathrmx, mathrmy\ in \3, 4\. Then among the statements (S_1) : The number of elements in R is 18, and (S_2) : The relation R is symmetric but neither reflexive nor transitive
  • A. both are true
  • B. both are false
  • C. only (mathrmS_2) is true
  • D. only (mathbfS_1) is true

Solution

### Related Formula max(x,y) = max(y,x) ### Core Logic Enumerate order metrics generated by the max mapping filter to assess population sizes and map properties against equivalence rule standards. ### Step 1: Enumerate Set Components Listing combinations matching the upper caps constraint parameters: R = \(0, 3), (3, 0), (0, 4), (4, 0), (1, 3), (3, 1), (1, 4), (4, 1), (2, 3), (3, 2), (2, 4), (4, 2), (3, 3), (3, 4), (4, 3), (4, 4)\ Total element count equals 16 items. Therefore, statement S_1 is false. ### Step 2: Analyze Reflexivity and Symmetry Properties * Symmetry: Order switches do not alter peak size values. Since (x,y) in R implies (y,x) in R, symmetry holds. * Reflexivity: Disjoint small pairs like (0,0) present peak values below target requirements, breaking reflexivity equations. ### Step 3: Test Transitivity Bounds Pick subset tracking variables showing breakdown trends: (0,3) in R quad textand quad (3,1) in R However, direct boundary tracking combination elements (0,1) notin R because max(0,1) = 1 notin \3,4\. Thus, transitivity fails. Only S_2 maps correctly. ### Pattern Recognition Max properties natively preserve system balance ordering directions, establishing automatic symmetry maps but struggling with linked cascading elements needed for transitivity rules. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Mathematics: Relations and Functions
Rankbit System
JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%) | JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%)