Example 5 - Chapter 13 Class 11 Limits and Derivatives
Last updated at May 29, 2018 by Teachoo
Last updated at May 29, 2018 by Teachoo
Transcript
Example 5 Find the derivative at x = 2 of the function f(x) = 3x. f (x) = 3x We know that, f’(x) = limh→0 f x+h−f(x)h Now, f(x) = 3x So, f(x + h) = 3 (x + h) f’ (x) = limh→0 3 x + h − 3 (x)h Putting x = 2 f’ (2) = limh→0 3 2 + h − 3 (2)h = limh→0 6 + 3ℎ − 6h = limh→0 3ℎ + 0h = limh→0 3ℎh = limh→0 3 = 3 Hence the derivative of the function f(x) at x = 2 is 3 i.e. f’(2) = 3
Derivatives by 1st principle - At a point
Derivatives by 1st principle - At a point
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