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Let f:[-1,oo] in [-1,oo] be a function g...

Let `f:[-1,oo] in [-1,oo]` be a function given `f(x)=(x+1)^(2)-1, x ge -1`
Statement-1: The set `[x:f(x)=f^(-1)(x)]={0,1}`
Statement-2: f is a bijection.

A

Statement 1 is ture, statement 2 is true, statement 2 is a correct explanation for statement 1.

B

Statement 1 is ture, statement 2 is true, statement 2 is not a correct explanation for statement 1.

C

Statement 1 is ture, statement 2 is false.

D

Statement 1 is false, statement 2 is true.

Text Solution

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The correct Answer is:
To solve the problem, we need to analyze the function \( f(x) = (x + 1)^2 - 1 \) for \( x \geq -1 \) and check the validity of both statements provided. ### Step 1: Determine the function \( f(x) \) Given: \[ f(x) = (x + 1)^2 - 1 \] ### Step 2: Simplify the function Let's simplify \( f(x) \): \[ f(x) = (x + 1)^2 - 1 = x^2 + 2x + 1 - 1 = x^2 + 2x \] ### Step 3: Check if \( f \) is a bijection A function is a bijection if it is both one-to-one (injective) and onto (surjective). #### Check for injectivity (one-to-one): To check if \( f \) is one-to-one, we can find the derivative \( f'(x) \): \[ f'(x) = 2x + 2 \] Since \( f'(x) \) is positive for \( x \geq -1 \) (as \( 2x + 2 \geq 0 \)), the function is increasing in this interval. Therefore, \( f \) is injective. #### Check for surjectivity (onto): To check if \( f \) is onto, we need to see if every \( y \) in the codomain has a corresponding \( x \) in the domain such that \( f(x) = y \). The range of \( f(x) \) can be found by evaluating the function at the endpoints of the domain. - At \( x = -1 \): \[ f(-1) = (-1 + 1)^2 - 1 = 0 - 1 = -1 \] - As \( x \to \infty \): \[ f(x) \to \infty \] Thus, the range of \( f \) is \( [-1, \infty) \). However, since we are not given the codomain explicitly, we cannot conclude that \( f \) is onto. ### Conclusion for Statement 2: Since we cannot confirm that \( f \) is onto, Statement 2 is **false**. ### Step 4: Solve \( f(x) = f^{-1}(x) \) To find the set \( \{ x : f(x) = f^{-1}(x) \} \), we first need to find \( f^{-1}(x) \). 1. Set \( y = f(x) \): \[ y = x^2 + 2x \] 2. Rearranging gives: \[ x^2 + 2x - y = 0 \] 3. Using the quadratic formula: \[ x = \frac{-2 \pm \sqrt{(2)^2 + 4y}}{2} = -1 \pm \sqrt{1 + y} \] Thus, \[ f^{-1}(y) = -1 + \sqrt{1 + y} \quad \text{(since we take the positive root for } x \geq -1\text{)} \] ### Step 5: Set up the equation \( f(x) = f^{-1}(x) \) Now we set: \[ f(x) = f^{-1}(x) \] This gives: \[ x^2 + 2x = -1 + \sqrt{1 + x} \] ### Step 6: Solve the equation Squaring both sides: \[ (x^2 + 2x + 1)^2 = 1 + x \] This leads to: \[ x^2 + 2x + 1 = \sqrt{1 + x} \] Now let's find the roots: 1. Rearranging gives: \[ x^2 + 2x + 1 - x = 0 \implies x^2 + x + 1 = 0 \] This quadratic has roots: \[ x = 0, -1 \] ### Conclusion for Statement 1: The valid solutions are \( x = 0 \) and \( x = 1 \). Therefore, Statement 1 is **true**. ### Final Answer: - Statement 1 is true: \( \{ x : f(x) = f^{-1}(x) \} = \{0, 1\} \) - Statement 2 is false: \( f \) is not necessarily a bijection.

To solve the problem, we need to analyze the function \( f(x) = (x + 1)^2 - 1 \) for \( x \geq -1 \) and check the validity of both statements provided. ### Step 1: Determine the function \( f(x) \) Given: \[ f(x) = (x + 1)^2 - 1 \] ...
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