Check sibling questions

If  y = log ((1 - x 2 )/(1 + x 2 )),then dy/dx is equal to

(A) ใ€–4x 3 /(1-x 4

(B) (-4x)/(1-x 4 )

(C) 1/(4-x 4

(D) (-4x 3 )/(1-x 4 )


Transcript

Question 19 If y = log ((1 โˆ’ ๐‘ฅ^2)/(1 + ๐‘ฅ^2 )),then ๐‘‘๐‘ฆ/๐‘‘๐‘ฅ is equal to (A) ใ€–4๐‘ฅใ€—^3/(1โˆ’๐‘ฅ^4 ) (B) (โˆ’4๐‘ฅ)/(1โˆ’๐‘ฅ^4 ) (C) 1/(4โˆ’๐‘ฅ^4 ) (D) (โˆ’4๐‘ฅ^3)/(1โˆ’๐‘ฅ^4 ) y=log((1 โˆ’ ๐‘ฅ^2)/(1 +ใ€– ๐‘ฅใ€—^2 )) ๐ฒ=๐ฅ๐จ๐ (๐Ÿโˆ’๐’™^๐Ÿ )โˆ’๐ฅ๐จ๐ โกใ€–(๐Ÿ+๐’™^๐Ÿ)ใ€— Differentiating wrt ๐‘ฅ ๐’…๐’š/๐’…๐’™=๐‘‘(log(1 โˆ’ ๐‘ฅ^2 ) โˆ’ logโกใ€–(1 + ๐‘ฅ^2)ใ€— )/๐‘‘๐‘ฅ =๐‘‘(log(1 โˆ’ ๐‘ฅ^2 ))/๐‘‘๐‘ฅโˆ’๐‘‘(log(1 + ๐‘ฅ^2 ))/๐‘‘๐‘ฅ =๐Ÿ/((๐Ÿ โˆ’ ๐’™^๐Ÿ ) ) ๐’…(๐Ÿ โˆ’ ๐’™^๐Ÿ )/๐’…๐’™โˆ’๐Ÿ/((๐Ÿ + ๐’™^๐Ÿ ) ) ๐’…(๐Ÿ + ๐’™^๐Ÿ )/๐’…๐’™ =1/((1 โˆ’ ๐‘ฅ^2 ) )(0โˆ’2๐‘ฅ)โˆ’1/((1 + ๐‘ฅ^2 ) ) (0+2๐‘ฅ) =(โˆ’2๐‘ฅ)/((1 โˆ’ ๐‘ฅ^2 ) )โˆ’2๐‘ฅ/((1 + ๐‘ฅ^2 ) ) =โˆ’2๐‘ฅ(1/((1 โˆ’ใ€– ๐‘ฅใ€—^2 ) )+1/((1 +ใ€– ๐‘ฅใ€—^2 ) )) =โˆ’2๐‘ฅ((1 + ๐‘ฅ^2 + 1 โˆ’ใ€– ๐‘ฅใ€—^2)/(1 โˆ’ ๐‘ฅ^2 )(1 + ๐‘ฅ^2 ) ) =โˆ’2๐‘ฅ(2/(1 โˆ’ใ€– ๐‘ฅใ€—^2 )(1 + ๐‘ฅ^2 ) ) =(โˆ’๐Ÿ’๐’™)/(๐Ÿ โˆ’ ๐’™^๐Ÿ’ ) So, the correct answer is (B)

  1. Chapter 5 Class 12 Continuity and Differentiability
  2. Serial order wise

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