Let f: mathbbR to mathbbR be a continuous function satisfying f(0) = 1 and f(2x) - f(x) = x for all x in mathbbR. If lim_n to infty left\ f(x) - fleft(fracx2^nright) right\ = G(x), then sum_r=1^10 G(r^2) is equal to

Solution & Explanation

### Related Formula Sum of first n squares: sum_r=1^n r^2 = fracn(n+1)(2n+1)6 ### Core Logic From functional relation f(x) - fleft(fracx2right) = fracx2. Write a telescoping sequence by scaling variable down: fleft(fracx2right) - fleft(fracx4right) = fracx4 fleft(fracx4right) - fleft(fracx8right) = fracx8 dots fleft(fracx2^n-1right) - fleft(fracx2^nright) = fracx2^n ### Step 1: Evaluate the Limit Definition Summing all equations creates a telescoping sum on the left side: f(x) - fleft(fracx2^nright) = xleft(frac12 + frac14 + dots + frac12^nright) = xleft(1 - frac12^nright) Taking the limit as n to infty: G(x) = lim_n to infty xleft(1 - frac12^nright) = x ### Step 2: Final Sum Evaluation We need to compute sum_r=1^10 G(r^2) = sum_r=1^10 r^2: sum_r=1^10 r^2 = frac10 times 11 times 216 = 385 ### Pattern Recognition Linear iterative arguments of type f(2x)-f(x)=x naturally condense into geometric progression properties via geometric series limits. Always look for telescoping patterns in infinite limits of difference terms. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Mathematics: Sequence and Series Class 12 Mathematics: Relations and Functions

Reference Study Guides

More Sets, Relations and Functions Previous-Year Questions — Page 10

Q6 jee_main_2024_31_jan_morning Composition of Functions
If f(x) = frac4x + 36x - 4, x neq frac23 and (fof)(x) = g(x), where g : mathbbR - left\frac23right\ to mathbbR - left\frac23right\, then (gogog)(4) is equal to
  • A. -frac1920
  • B. frac1920
  • C. -4
  • D. 4

Solution

### Core Logic f(x) = frac4x + 36x - 4 Compute g(x) = f(f(x)): g(x) = frac4left(frac4x + 36x - 4right) + 36left(frac4x + 36x - 4right) - 4 = frac16x + 12 + 18x - 1224x + 18 - 24x + 16 = frac34x34 = x ### Step 1: Composition Evaluation Since g(x) = x, g is the identity function. (gogog)(4) = g(g(g(4))) = 4 ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Maths: Relations and Functions
Q29 jee_main_2024_31_jan_morning Equivalence Relations
Let A = \1, 2, 3, 4\ and R = \(1, 2), (2, 3), (1, 4)\ be a relation on A. Let S be the equivalence relation on A such that R subset S and the number of elements in S is n. Then, the minimum value of n is
Numerical Answer. Answer: 16 to 16

Solution

### Core Logic S must be reflexive, symmetric, and transitive, containing (1,2), (2,3), and (1,4). Symmetric property forces (2,1), (3,2), (4,1) in S. Transitive property: (1,2) and (2,3) implies (1,3) in S. Symmetric implies (3,1) in S. (4,1) and (1,2) implies (4,2) in S. Symmetric implies (2,4) in S. (4,1) and (1,3) implies (4,3) in S. Symmetric implies (3,4) in S. ### Step 1: Universal Relation Since 1 is related to 2, 3, 4 and the relation is an equivalence relation (which creates partitions), all elements 1, 2, 3, and 4 must fall into the same single equivalence class. Thus, S must contain all possible ordered pairs in A times A. ### Step 2: Final Count Number of elements in A times A = 4 times 4 = 16. Minimum value of n is 16. ### Pattern Recognition If a relation connects all elements in a set to each other through a chain, its equivalence closure is the universal relation A times A. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Maths: Relations and Functions

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