Let f(x) = { x 3 x 2 + 1 0 x 7 , x 1 2 x + l o g 2 ( b 2 4 ) , x > 1 .  Then the set of all values of b, for which f(x) has maximum value at x = 1, is:

Option 1 - <p>(-6, -2)</p>
Option 2 - <p>(2, 6)</p>
Option 3 - <p><span class="mathml" contenteditable="false"> <math> <mrow> <mrow> <mo>[</mo> <mrow> <mo>−</mo> <mn>6</mn> <mo>,</mo> <mrow> <mrow> <mo>−</mo> <mn>2</mn> </mrow> <mo>)</mo> </mrow> <mo>∪</mo> <mrow> <mo>(</mo> <mrow> <mn>2</mn> <mo>,</mo> <mtext> </mtext> <mtext> </mtext> <mn>6</mn> </mrow> </mrow> </mrow> <mo>]</mo> </mrow> </mrow> </math> </span></p>
Option 4 - <p><span class="mathml" contenteditable="false"> <math> <mrow> <mrow> <mo>[</mo> <mrow> <mo>−</mo> <mroot> <mrow> <mn>6</mn> </mrow> <mrow></mrow> </mroot> <mo>,</mo> <mrow> <mrow> <mo>−</mo> <mn>2</mn> </mrow> <mo>)</mo> </mrow> <mo>∪</mo> <mrow> <mo>(</mo> <mrow> <mn>2</mn> <mo>,</mo> <mroot> <mrow> <mn>6</mn> </mrow> <mrow></mrow> </mroot> </mrow> </mrow> </mrow> <mo>]</mo> </mrow> </mrow> </math> </span></p>
7 Views|Posted 4 months ago
Asked by Shiksha User
1 Answer
R
4 months ago
Correct Option - 3
Detailed Solution:

f ( x ) = { x 3 x 2 + 1 0 x 7 , x 1 2 x + l o g 2 ( b 2 4 ) , x > 1  

If f(x) has maximum value at x = 1 then

f ( 1 ) f ( 1 ) 2 + l o g 2 ( b 2 4 ) 1 1 + 1 0 7

l o g 2 ( b 2 4 ) 5 0 < b 2 4 3 2

b 2 4 > 0 b ( , 2 ) ( 2 , )         ……..(i)

A n d b 2 4 3 2 b [ 6 , 6 ]                      ……..(ii)

From (i) and (ii) we get  b [ 6 , 2 ) ( 2 , 6 ]  

 

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Maths Applications of Derivatives 2025

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