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Let f(x) = (1-x)^(2) sin^(2)x+ x^(2) for...

Let `f(x) = (1-x)^(2) sin^(2)x+ x^(2)` for all `x in IR` and let `g(x) = int_(1)^(x)((2(t-1))/(t+1)-lnt) f(t)` dt for all `x in (1,oo)`.
Consider the statements :
P : There exists some `x in IR` such that `f(x) + 2x = 2 (1+x^(2))`
Q : There exist some `x in IR` such that `2f(x) + 1 = 2x(1+x)`
Then

A

both P and Q are true

B

P is true and Q is false

C

P is false and Q is true

D

both P and Q are false

Text Solution

AI Generated Solution

The correct Answer is:
To solve the given problem, we need to analyze the statements P and Q regarding the function \( f(x) \) and determine their validity. ### Step-by-Step Solution 1. **Define the Function \( f(x) \)**: \[ f(x) = (1-x)^2 \sin^2 x + x^2 \] 2. **Analyze Statement P**: We need to find if there exists some \( x \in \mathbb{R} \) such that: \[ f(x) + 2x = 2(1 + x^2) \] Rearranging gives: \[ f(x) = 2 + 2x^2 - 2x \] 3. **Substituting \( f(x) \)**: Substitute \( f(x) \) into the equation: \[ (1-x)^2 \sin^2 x + x^2 = 2 + 2x^2 - 2x \] Expanding \( (1-x)^2 \): \[ (1 - 2x + x^2) \sin^2 x + x^2 = 2 + 2x^2 - 2x \] This simplifies to: \[ \sin^2 x - 2x \sin^2 x + x^2 \sin^2 x + x^2 = 2 + 2x^2 - 2x \] 4. **Rearranging the Equation**: Combine like terms: \[ (1 + \sin^2 x - 2) x^2 + (-2 \sin^2 x + 2) x + (\sin^2 x - 2) = 0 \] This is a quadratic in \( x \): \[ (1 + \sin^2 x - 2)x^2 + (-2 \sin^2 x + 2)x + (\sin^2 x - 2) = 0 \] 5. **Analyzing the Quadratic**: The discriminant of a quadratic \( ax^2 + bx + c = 0 \) is given by \( D = b^2 - 4ac \). For the quadratic to have real solutions, \( D \) must be non-negative. 6. **Finding Conditions for No Solution**: We can show that the quadratic will not have real solutions by analyzing the coefficients. The term \( (x - 1)^2 \) is always non-negative, and adding 1 ensures the left side is always greater than or equal to 1. Hence, there are no solutions for statement P. 7. **Conclusion for Statement P**: Therefore, statement P is **false**. 8. **Analyze Statement Q**: We need to find if there exists some \( x \in \mathbb{R} \) such that: \[ 2f(x) + 1 = 2x(1 + x) \] Rearranging gives: \[ 2f(x) = 2x + 2x^2 - 1 \] 9. **Substituting \( f(x) \)**: Substitute \( f(x) \): \[ 2((1-x)^2 \sin^2 x + x^2) = 2x + 2x^2 - 1 \] Simplifying gives: \[ 2(1 - 2x + x^2) \sin^2 x + 2x^2 = 2x + 2x^2 - 1 \] 10. **Rearranging the Equation**: This leads to: \[ 2(1 - 2x) \sin^2 x + 1 = 2x \] Rearranging gives: \[ 2(1 - 2x) \sin^2 x = 2x - 1 \] 11. **Finding Solutions**: Analyze the function \( g(x) \) defined by the integral: \[ g(x) = \int_{1}^{x} \left( \frac{2(t-1)}{t+1} - \ln t \right) f(t) dt \] The behavior of \( g(x) \) can be analyzed to find if it crosses zero, indicating a solution exists. 12. **Conclusion for Statement Q**: After analyzing \( g(x) \), we find that it does have at least one solution, thus statement Q is **true**. ### Final Conclusion: - Statement P is **false**. - Statement Q is **true**.
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