Check sibling questions

If y = log⁡(cos⁡ e x ), then dy/dx is :

(a) cose (x-1)   (b) e (-x) cos e x
(c) e x sine x    (d) -e x tan e x

 

This question is inspired from Ex 5.4, 5 - Chapter 5 Class 12 - Continuity and Differentiability


Transcript

Question 18 If y = ๐‘™๐‘œ๐‘”โก(๐‘๐‘œ๐‘ โกใ€–๐‘’^๐‘ฅ ใ€— ), then ๐‘‘๐‘ฆ/๐‘‘๐‘ฅ is : (a) ๐‘๐‘œ๐‘ ๐‘’^(๐‘ฅโˆ’1) (b) ๐‘’^(โˆ’๐‘ฅ) "cos" ๐‘’^๐‘ฅ (c) ๐‘’^๐‘ฅ ๐‘ ๐‘–๐‘›๐‘’^๐‘ฅ (d) ใ€–โˆ’๐‘’ใ€—^๐‘ฅ " tan" ใ€– ๐‘’ใ€—^๐‘ฅ Given ๐‘ฆ = ใ€–log ใ€—โก(cosโกใ€–๐‘’^๐‘ฅ ใ€— ) Differentiating both sides ๐‘ค.๐‘Ÿ.๐‘ก.๐‘ฅ ๐‘‘(๐‘ฆ)/๐‘‘๐‘ฅ = ๐‘‘(ใ€–log ใ€—โก(cosโกใ€–๐‘’^๐‘ฅ ใ€— ) )/๐‘‘๐‘ฅ ๐‘‘๐‘ฆ/๐‘‘๐‘ฅ = 1/cosโกใ€–๐‘’^๐‘ฅ ใ€— . ๐‘‘(cosโกใ€–๐‘’^๐‘ฅ ใ€— )/๐‘‘๐‘ฅ = 1/cosโกใ€–๐‘’^๐‘ฅ ใ€— . (โˆ’sinโกใ€–๐‘’^๐‘ฅ ใ€— ) . ๐‘‘(๐‘’^๐‘ฅ )/๐‘‘๐‘ฅ = 1/cosโกใ€–๐‘’^๐‘ฅ ใ€— . (โˆ’sinโกใ€–๐‘’^๐‘ฅ ใ€— ) . ๐‘’^๐‘ฅ = (โˆ’sinโกใ€–๐‘’^๐‘ฅ ใ€—)/cosโกใ€–๐‘’^๐‘ฅ ใ€— . ๐‘’^๐‘ฅ = โˆ’tanโกใ€–๐‘’^๐‘ฅ ใ€— . ๐‘’^๐‘ฅ = โˆ’๐’†^๐’™ . ๐’•๐’‚๐’โกใ€–๐’†^๐’™ ใ€— So, the correct answer is (D)

  1. Class 12
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About the Author

Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science and Computer Science at Teachoo