Question
Download Solution PDFComprehension
Let the function f(x) = x 2 + 9
Consider the following statements:
I. f(x) is an increasing function.
II. f(x) has local maximum at x = 0
Which of the statements given above is/are correct?
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFCalculation:
Given,
The function is \( f(x) = x^2 + 9 \).
Statement I: f(x) is an increasing function.
The derivative of f(x) is:
\( f'(x) = \frac{d}{dx}(x^2 + 9) = 2x \)
When \(( x > 0 )\), \(( f'(x) > 0 )\), so (f(x) is increasing.
When (x < 0), f'(x) < 0 ), so f(x) is decreasing.
At (x = 0), ( f'(x) = 0 ), meaning the function is neither increasing nor decreasing at this point.
Hence, f(x) is not entirely increasing. It is increasing for (x > 0) and decreasing for ( x < 0).
Statement II: f(x) has local maximum at x = 0
Since the function\( f(x) = x^2 + 9 \) is a parabola opening upwards (because the coefficient of x2 is positive), it has a global minimum at x = 0, not a local maximum.
Conclusion:
- Statement I is incorrect because the function is not entirely increasing. It is increasing for x > 0 and decreasing for x < 0 .
- Statement II is incorrect because the function has a global minimum at x = 0, not a local maximum.
Hence, the correct answer is Option 4.
Last updated on Jul 8, 2025
->UPSC NDA Application Correction Window is open from 7th July to 9th July 2025.
->UPSC had extended the UPSC NDA 2 Registration Date till 20th June 2025.
-> A total of 406 vacancies have been announced for NDA 2 Exam 2025.
->The NDA exam date 2025 has been announced. The written examination will be held on 14th September 2025.
-> The selection process for the NDA exam includes a Written Exam and SSB Interview.
-> Candidates who get successful selection under UPSC NDA will get a salary range between Rs. 15,600 to Rs. 39,100.
-> Candidates must go through the NDA previous year question paper. Attempting the NDA mock test is also essential.