Home
Class 12
MATHS
Let f(x)=x^2 + 3x-3,x leq 0. If n point...

Let `f(x)=x^2 + 3x-3,x leq 0`. If n points `x_1, x_2, x_3,.....,x_n` are so chosen on the x-axis such that 1/n summationf^-1(xi)=f(1/n summation i=1 to n(xi)) (2) summationi=1 to n f^-1(xi)=summation i=1 to n (xi,)where f^-1 denotes the inverse of f, Then the AM of xi's is a)1 b)2 c)3 d)4

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to analyze the given function and the conditions provided. Let's break it down step by step. ### Step 1: Understand the Function The function given is: \[ f(x) = x^2 + 3x - 3 \] for \( x \leq 0 \). ### Step 2: Find the Inverse Function \( f^{-1}(x) \) To find the inverse, we first set \( y = f(x) \): \[ y = x^2 + 3x - 3 \] Rearranging gives: \[ x^2 + 3x - (y + 3) = 0 \] This is a quadratic equation in \( x \). We can use the quadratic formula: \[ x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \] where \( a = 1, b = 3, c = -(y + 3) \). Calculating the discriminant: \[ b^2 - 4ac = 3^2 - 4(1)(-(y + 3)) = 9 + 4(y + 3) = 4y + 21 \] Thus, the inverse function is: \[ f^{-1}(y) = \frac{-3 \pm \sqrt{4y + 21}}{2} \] Since we are considering \( x \leq 0 \), we take the negative root: \[ f^{-1}(y) = \frac{-3 - \sqrt{4y + 21}}{2} \] ### Step 3: Apply the Given Conditions We have two conditions: 1. \( \frac{1}{n} \sum_{i=1}^{n} f^{-1}(x_i) = f\left(\frac{1}{n} \sum_{i=1}^{n} x_i\right) \) 2. \( \sum_{i=1}^{n} f^{-1}(x_i) = \sum_{i=1}^{n} x_i \) Let \( t = \frac{1}{n} \sum_{i=1}^{n} x_i \). Then from the first condition, we have: \[ \frac{1}{n} \sum_{i=1}^{n} f^{-1}(x_i) = f(t) \] ### Step 4: Calculate \( f(t) \) Substituting \( t \) into the function: \[ f(t) = t^2 + 3t - 3 \] ### Step 5: Substitute into the First Condition From the first condition: \[ \frac{1}{n} \sum_{i=1}^{n} f^{-1}(x_i) = f(t) \] This implies: \[ \sum_{i=1}^{n} f^{-1}(x_i) = n f(t) \] ### Step 6: Substitute into the Second Condition From the second condition: \[ \sum_{i=1}^{n} f^{-1}(x_i) = \sum_{i=1}^{n} x_i \] Thus, we have: \[ n f(t) = \sum_{i=1}^{n} x_i \] ### Step 7: Equate the Two Expressions Setting the two expressions for \( \sum_{i=1}^{n} f^{-1}(x_i) \) equal gives: \[ n f(t) = n t \] This simplifies to: \[ f(t) = t \] ### Step 8: Solve for \( t \) Substituting \( f(t) \): \[ t^2 + 3t - 3 = t \] Rearranging gives: \[ t^2 + 2t - 3 = 0 \] ### Step 9: Factor the Quadratic Factoring: \[ (t - 1)(t + 3) = 0 \] Thus, \( t = 1 \) or \( t = -3 \). Since \( t \) represents the average of \( x_i \) and must be non-negative, we have: \[ t = 1 \] ### Conclusion The arithmetic mean of the \( x_i \)'s is: \[ \text{AM} = t = 1 \] ### Final Answer The arithmetic mean of \( x_i \)'s is \( \boxed{1} \).
Promotional Banner

Topper's Solved these Questions

  • FUNCTIONS

    ARIHANT MATHS ENGLISH|Exercise FUNCTION EXERCISE 7: Subjective Type Questions|1 Videos
  • FUNCTIONS

    ARIHANT MATHS ENGLISH|Exercise Exercise (Questions Asked In Previous 13 Years Exam)|24 Videos
  • FUNCTIONS

    ARIHANT MATHS ENGLISH|Exercise Exercise (Single Integer Answer Type Questions)|31 Videos
  • ESSENTIAL MATHEMATICAL TOOLS

    ARIHANT MATHS ENGLISH|Exercise Exercise (Single Integer Answer Type Questions)|3 Videos
  • GRAPHICAL TRANSFORMATIONS

    ARIHANT MATHS ENGLISH|Exercise Exercise (Questions Asked In Previous 13 Years Exam)|10 Videos

Similar Questions

Explore conceptually related problems

If x_1, x_2, .....x_n are n observations such that sum_(i=1)^n (x_i)^2=400 and sum_(i=1)^n x_i=100 then possible values of n among the following is

Let f(n) = [1/2 + n/100] where [x] denote the integral part of x. Then the value of sum_(n=1)^100 f(n) is

If x_1,x_2,.......,x_n are n values of a variable X such that sum_(i=1)^n (x_i-2)=110 and sum_(i=1)^n(x_i-5) =20 . Find the value of n and the mean.

If the mean of the set of numbers x_1,x_2, x_3, ..., x_n is barx, then the mean of the numbers x_i+2i, 1 lt= i lt= n is

The mean deviation for n observations x_1, x_2, ......... , x_n from their mean X is given by (a) sum_(i=1)^n(x_i- X ) (b) 1/nsum_(i=1)^n(x_i- X ) (c) sum_(i=1)^n(x_i- X )^2 (d) 1/nsum_(i=1)^n(x_i- X )^2

The mean deviation for n observations x_1, x_2, ......... , x_n from their mean X is given by (a) sum_(i=1)^n(x_i- X ) (b) 1/nsum_(i=1)^n|x_i- X | (c) sum_(i=1)^n(x_i- X )^2 (d) 1/nsum_(i=1)^n(x_i- X )^2

f:N to N, where f(x)=x-(-1)^(x) , Then f is

Let f (x ) = | 3 - | 2- | x- 1 |||, AA x in R be not differentiable at x _ 1 , x _ 2 , x _ 3, ….x_ n , then sum _ (i= 1 ) ^( n ) x _ i^2 equal to :

If sum_(i=1)^200 sin^-1 x_i=100pi, then sum _(i=1)^200 x_i^2 is equal to

If x!=1\ a n d\ f(x)=(x+1)/(x-1) is a real function, then f(f(f(2))) is (a) 1 (b) 2 (c) 3 (d) 4