Example 15 - Find derivative of f(x) =  x + 1/x - Class 11 NCERT - Examples

Example 15 - Chapter 13 Class 11 Limits and Derivatives - Part 2
Example 15 - Chapter 13 Class 11 Limits and Derivatives - Part 3


Transcript

Example 15 (Method 1) Find the derivative of f(x) = x + 1﷮x﷯ f(x) = 𝑥 + 1 ﷮𝑥﷯ = 𝑥﷮𝑥﷯ + 1﷮𝑥﷯ = 1 + 1﷮𝑥﷯ = 1 + (x) –1 Now, f’ (x) = (1 + (x) –1)’ = 0 + ( –1) x –1 – 1 = 0 – x –2 = – x –2 = −𝟏﷮ 𝒙﷮𝟐﷯﷯ Example 15 (Method 2) Find the derivative of f(x) = x + 1﷮x﷯ Given f(x) = 𝑥 + 1 ﷮𝑥﷯ Let u = x + 1 & v = x So, f(x) = 𝑢﷮𝑣﷯ Now, f’(x) = 𝑢﷮𝑣﷯﷯﷮′﷯ Using quotient rule f’(x) = 𝑢﷮′﷯𝑣 − 𝑣﷮′﷯𝑢﷮ 𝑣﷮2﷯﷯ Finding u’ and v’ separately Finding u’ & v’ u = x + 1 u’ = 1 + 0 = 1 v = x v’ = 1 Now, f’(x) = 𝑢﷮𝑣﷯﷯﷮′﷯ = 𝑢﷮′﷯𝑣 − 𝑣﷮′﷯𝑢﷮ 𝑣﷮2﷯﷯ = 1 𝑥﷯ − 𝑥 + 1 ﷯1﷮ 𝑥﷮2﷯﷯ = 𝑥 − 𝑥 + 1﷮ 𝑥﷮2﷯﷯ = 𝟏﷮ 𝒙﷮𝟐﷯﷯

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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, Social Science, Physics, Chemistry, Computer Science at Teachoo.