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Statement-1 : f(x) = x^(4) - 3x^(2) + 4x...

Statement-1 : `f(x) = x^(4) - 3x^(2) + 4x-1` is many one into in `R rarr R`.
and
Statement-2 : If `f : R rarr R` is a polynomial of even degree it will neither be injective nor surjective.

A

Statement-1 is True, Statement-2 is True, Statement-2 is a correct explanation for Statement-1.

B

Statement-1 is True, Statement-2 is True, Statement-2 is NOT a correct explanation for Statement-1.

C

Statement -1 is False, Statement -2 is False

D

Statement -1 is False, Statement -2 is True

Text Solution

AI Generated Solution

The correct Answer is:
To determine the validity of the statements regarding the function \( f(x) = x^4 - 3x^2 + 4x - 1 \), we will analyze both statements step by step. ### Step 1: Analyze Statement 1 **Statement 1:** \( f(x) = x^4 - 3x^2 + 4x - 1 \) is many-one into \( \mathbb{R} \to \mathbb{R} \). 1. **Find the derivative of \( f(x) \)**: \[ f'(x) = \frac{d}{dx}(x^4 - 3x^2 + 4x - 1) = 4x^3 - 6x + 4 \] 2. **Set the derivative to zero to find critical points**: \[ 4x^3 - 6x + 4 = 0 \] This is a cubic equation. To analyze the behavior of \( f'(x) \), we can find the roots of this equation. 3. **Use the Rational Root Theorem or numerical methods** to find the roots. For simplicity, let's check for possible rational roots: - Testing \( x = -1 \): \[ f'(-1) = 4(-1)^3 - 6(-1) + 4 = -4 + 6 + 4 = 6 \quad (\text{not a root}) \] - Testing \( x = 0 \): \[ f'(0) = 4(0)^3 - 6(0) + 4 = 4 \quad (\text{not a root}) \] - Testing \( x = 1 \): \[ f'(1) = 4(1)^3 - 6(1) + 4 = 4 - 6 + 4 = 2 \quad (\text{not a root}) \] - Testing \( x = -2 \): \[ f'(-2) = 4(-2)^3 - 6(-2) + 4 = -32 + 12 + 4 = -16 \quad (\text{not a root}) \] Since we do not find simple rational roots, we can analyze the sign of \( f'(x) \) to determine the behavior of \( f(x) \). 4. **Analyze the sign of \( f'(x) \)**: - As \( x \to -\infty \), \( f'(x) \to -\infty \) (since the leading term \( 4x^3 \) dominates). - As \( x \to +\infty \), \( f'(x) \to +\infty \). - Since \( f'(x) \) is a cubic polynomial, it can change signs, indicating that \( f(x) \) has at least one local maximum and one local minimum. 5. **Conclusion for Statement 1**: Since \( f(x) \) has at least one local maximum and one local minimum, it is not one-one (injective), hence it is many-one. ### Step 2: Analyze Statement 2 **Statement 2:** If \( f: \mathbb{R} \to \mathbb{R} \) is a polynomial of even degree, it will neither be injective nor surjective. 1. **Understanding even degree polynomials**: - An even degree polynomial \( f(x) \) can be expressed as \( a_n x^n + a_{n-1} x^{n-1} + \ldots + a_1 x + a_0 \) where \( n \) is even. - Such polynomials tend to have a "U" shape or an inverted "U" shape. 2. **Injectivity**: - Since even degree polynomials can have local maxima and minima, they will not be injective (one-one). They can take the same value for different inputs. 3. **Surjectivity**: - The range of an even degree polynomial is limited; it cannot cover all real numbers. For example, a polynomial that opens upwards will have a minimum value and will not reach negative infinity. 4. **Conclusion for Statement 2**: Therefore, statement 2 is correct: even degree polynomials are neither injective nor surjective. ### Final Conclusion Both statements are correct: - Statement 1 is true: \( f(x) \) is many-one into \( \mathbb{R} \to \mathbb{R} \). - Statement 2 is true: Even degree polynomials are neither injective nor surjective.
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