Misc 27 - Find derivative: x2 cos pi/4 / sin x - Class 11 - Derivatives by formula - sin & cos

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Slide78.JPG

  1. Chapter 13 Class 11 Limits and Derivatives
  2. Serial order wise

Transcript

Misc 27 Find the derivative of the following functions (it is to be understood that a, b, c, d, p, q, r and s are fixed non-zero constants and m and n are integers): x2 cos ﷮ π﷮4﷯﷯﷮ sin﷮x﷯﷯ Let f (x) = 𝑥2 cos ﷮ 𝜋﷮4﷯﷯﷮sin x﷯ Let u = x2 cos 𝜋﷮4﷯ & v = sin x So, f(x) = 𝑢﷮𝑣﷯ ∴ f’(x) = 𝑢﷮𝑣﷯﷯﷮′﷯ Using quotient rule f’(x) = 𝑢﷮′﷯𝑣 − 𝑣﷮′﷯𝑢﷮ 𝑣﷮2﷯﷯ Finding u’ & v’ u = x2 cos 𝜋﷮4﷯ u’ = 2x2 –1 cos 𝜋﷮4﷯ = 2x cos 𝜋﷮4﷯ & v = sin x v’= cos x Now, f’(x) = 𝑢﷮𝑣﷯﷯﷮′﷯ = 𝑢﷮′﷯𝑣 − 𝑣﷮′﷯𝑢﷮ 𝑣﷮2﷯﷯ = 2𝑥 cos﷮ 𝜋﷮4﷯﷯ ( sin﷮𝑥)﷯ −( cos﷮𝑥) ( 𝑥﷮2﷯ cos﷮ 𝜋﷮4﷯) ﷯﷯﷮ 𝑠𝑖𝑛﷮2﷯ 𝑥﷯ = 2𝑥 𝑠𝑖𝑛 𝑥 cos ﷮ 𝜋﷮4﷯﷯ − 𝑥﷮2﷯ cos﷮𝑥 . cos ﷮ 𝜋﷮4﷯﷯﷯﷮ 𝑠𝑖𝑛﷮2﷯ 𝑥﷯ = 𝒙 𝐜𝐨𝐬 ﷮ 𝝅﷮𝟒﷯﷯ (𝟐 𝐬𝐢𝐧﷮𝒙 − 𝒙 𝐜𝐨𝐬﷮𝒙) ﷯﷯﷮ 𝒔𝒊𝒏﷮𝟐﷯ 𝒙﷯

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Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 8 years. He provides courses for Maths and Science at Teachoo. You can check his NCERT Solutions from Class 6 to 12.