This question is similar to Chapter 5 Class 12 Continuity and Differentiability - Ex 5.5

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Question 23 (B) - Differentiate (cos x)^x with respect to x [Video] - CBSE Class 12 Sample Paper for 2025 Boards

part 2 - Question 23 (B) - CBSE Class 12 Sample Paper for 2025 Boards - Solutions of Sample Papers and Past Year Papers - for Class 12 Boards - Class 12
part 3 - Question 23 (B) - CBSE Class 12 Sample Paper for 2025 Boards - Solutions of Sample Papers and Past Year Papers - for Class 12 Boards - Class 12

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Question 23 (B) Differentiate the following function with respect to x:(cos π‘₯)^π‘₯; (where β”œ π‘₯∈(0,πœ‹/2)).Let 𝑦 = γ€–(π‘π‘œπ‘ β‘π‘₯ ) γ€—^π‘₯ We use log differentiation Taking log both sides . log⁑𝑦 = logγ€– (π‘π‘œπ‘ β‘π‘₯ ) γ€—^π‘₯ π’π’π’ˆβ‘π’š = 𝒙 . π’π’π’ˆ (𝒄𝒐𝒔⁑𝒙 ) Differentiating both sides 𝑀.π‘Ÿ.𝑑.π‘₯. (As π‘™π‘œπ‘”β‘(π‘Ž^𝑏 )=𝑏 . π‘™π‘œπ‘”β‘π‘Ž) 𝑑(log⁑𝑦 )/𝑑π‘₯ = (𝑑(π‘₯ . log⁑(cos⁑π‘₯ ) ) )/𝑑π‘₯ 𝑑(log⁑𝑦 )/𝑑𝑦 . 𝑑𝑦/𝑑π‘₯ = (𝑑(π‘₯ . log⁑(cos⁑π‘₯ ) ) )/𝑑π‘₯ 1/𝑦 (𝑑𝑦/𝑑π‘₯) = (𝑑(π‘₯ . log⁑(cos⁑π‘₯ ) ) )/𝑑π‘₯ 1/𝑦 (𝑑𝑦/𝑑π‘₯) = 𝑑π‘₯/𝑑π‘₯ log⁑〖( π‘π‘œπ‘  π‘₯)γ€—+π‘₯ (𝑑(π‘™π‘œπ‘”β‘(π‘π‘œπ‘ β‘π‘₯ ) ) )/𝑑π‘₯ 1/𝑦 (𝑑𝑦/𝑑π‘₯) = log⁑〖(cos⁑π‘₯)γ€—+π‘₯ Γ— 1/cos⁑π‘₯ Γ— (π‘π‘œπ‘  π‘₯)^β€² 1/𝑦 (𝑑𝑦/𝑑π‘₯) = log⁑〖(cos⁑π‘₯)γ€—+π‘₯/cos⁑π‘₯ Γ— (βˆ’sin⁑π‘₯ ) Using product Rule As (𝑒𝑣)’ = 𝑒’𝑣 + 𝑣’𝑒 1/𝑦 (𝑑𝑦/𝑑π‘₯) = log⁑〖(cos⁑π‘₯)γ€—βˆ’π‘₯ tan⁑π‘₯ 𝑑𝑦/𝑑π‘₯ = 𝑦[log⁑(cos⁑π‘₯ )βˆ’π‘₯ tan⁑π‘₯ ] Putting value of 𝑦 π’…π’š/𝒅𝒙 = (πœπ¨π¬β‘π’™ )^𝒙 [π’π’π’ˆβ‘(𝒄𝒐𝒔⁑𝒙 )βˆ’π’™ 𝒕𝒂𝒏⁑𝒙 ]

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Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 15 years. He provides courses for Maths, Science and Computer Science at Teachoo