Let f : R -> R be a function defined by f(x) = ( x 3 ) n 1 ( x 5 ) n 2 , n 1 , n 2 N .  Then which of the following is NOT true?

Option 1 - <p>For n<sub>1</sub> = 3, n<sub>2</sub> = 4, there exists <span class="mathml" contenteditable="false"> <math> <mrow> <mi>α</mi> <mo>∈</mo> <mrow> <mo>(</mo> <mrow> <mn>3</mn> <mo>,</mo> <mn>5</mn> </mrow> <mo>)</mo> </mrow> </mrow> </math> </span>&nbsp;where f attains local&nbsp; maxima.</p>
Option 2 - <p>For n<sub>1</sub> = 4, n<sub>2</sub> = 3, there exists <span contenteditable="false"> <math> <mrow> <mi>α</mi> <mo>∈</mo> <mrow> <mo>(</mo> <mrow> <mn>3</mn> <mo>,</mo> <mn>5</mn> </mrow> <mo>)</mo> </mrow> </mrow> </math> </span>&nbsp;where f attains local minima.</p>
Option 3 - <p>For n<sub>1</sub> = 3, n<sub>2</sub> = 5, there exists <span contenteditable="false"> <math> <mrow> <mi>α</mi> <mo>∈</mo> <mrow> <mo>(</mo> <mrow> <mn>3</mn> <mo>,</mo> <mn>5</mn> </mrow> <mo>)</mo> </mrow> </mrow> </math> </span>where f attains local maxima.</p>
Option 4 - <p>For n<sub>1</sub> = 4, n<sub>2</sub> = 6, there exists <span contenteditable="false"> <math> <mrow> <mi>α</mi> <mo>∈</mo> <mrow> <mo>(</mo> <mrow> <mn>3</mn> <mo>,</mo> <mn>5</mn> </mrow> <mo>)</mo> </mrow> </mrow> </math> </span>where f attains local maxima.</p>
2 Views|Posted 4 months ago
Asked by Shiksha User
1 Answer
V
4 months ago
Correct Option - 3
Detailed Solution:

f ' ( x ) = n 1 f ( x ) x 3 + n 2 f ( x ) x 5

= f ( x ) ( n 1 + n 2 ) ( x 3 ) ( x 5 ) ( x ( 5 n 1 + 3 n 2 ) n 1 + n 2 )

f ' ( x ) = ( x 3 ) n 1 1 ( x 5 ) n 2 1 ( n 1 + n 2 ) ( x ( 5 n 1 + 3 n 2 ) n 1 + n 2 l )

option (C) is incorrect, there will be minima.

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Maths Applications of Derivatives 2025

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