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f(x)={{:(3x^(2)+12x-1,-1lexle2),(37-x","...

`f(x)={{:(3x^(2)+12x-1,-1lexle2),(37-x",",2ltxle3):}`
Which of the following statements is /are correct?
1. f(x) is increasing in the interval [-1,2].
2. f(x) is decreasing in the interval (2,3].
Select the correct answer using the code given below:

A

1 only

B

2 only

C

Both 1 and 2

D

Neither 1 nor 2

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to analyze the function \( f(x) \) defined in two parts: 1. \( f(x) = 3x^2 + 12x - 1 \) for \( -1 \leq x \leq 2 \) 2. \( f(x) = 37 - x \) for \( 2 < x \leq 3 \) We will check the two statements given in the question: ### Step 1: Analyze the first statement **Statement 1:** \( f(x) \) is increasing in the interval \([-1, 2]\). To determine if \( f(x) \) is increasing, we need to find the derivative \( f'(x) \) for the interval \([-1, 2]\). 1. **Calculate the derivative:** \[ f'(x) = \frac{d}{dx}(3x^2 + 12x - 1) = 6x + 12 \] 2. **Check the sign of the derivative in the interval \([-1, 2]\):** - Choose a test point, say \( x = 1 \): \[ f'(1) = 6(1) + 12 = 18 \] Since \( f'(1) > 0 \), the function is increasing at this point. 3. **Check the endpoints:** - At \( x = -1 \): \[ f'(-1) = 6(-1) + 12 = 6 > 0 \] - At \( x = 2 \): \[ f'(2) = 6(2) + 12 = 24 > 0 \] Since \( f'(x) > 0 \) for all \( x \) in the interval \([-1, 2]\), we conclude that \( f(x) \) is increasing in this interval. ### Conclusion for Statement 1: **Statement 1 is correct.** ### Step 2: Analyze the second statement **Statement 2:** \( f(x) \) is decreasing in the interval \( (2, 3] \). 1. **For the interval \( (2, 3] \), the function is defined as:** \[ f(x) = 37 - x \] 2. **Calculate the derivative:** \[ f'(x) = \frac{d}{dx}(37 - x) = -1 \] 3. **Check the sign of the derivative:** Since \( f'(x) = -1 < 0 \) for all \( x \) in the interval \( (2, 3] \), the function is decreasing in this interval. ### Conclusion for Statement 2: **Statement 2 is correct.** ### Final Conclusion: Both statements are correct. ### Summary of Steps: 1. Calculate the derivative of \( f(x) \) for the first interval and check its sign. 2. Confirm that \( f(x) \) is increasing in the interval \([-1, 2]\). 3. Calculate the derivative of \( f(x) \) for the second interval and check its sign. 4. Confirm that \( f(x) \) is decreasing in the interval \( (2, 3] \).

To solve the problem, we need to analyze the function \( f(x) \) defined in two parts: 1. \( f(x) = 3x^2 + 12x - 1 \) for \( -1 \leq x \leq 2 \) 2. \( f(x) = 37 - x \) for \( 2 < x \leq 3 \) We will check the two statements given in the question: ### Step 1: Analyze the first statement ...
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