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Derivatives by 1st principle - At a point
Derivatives by 1st principle - At a point
Last updated at Nov. 30, 2019 by Teachoo
Maths Crash Course - Live lectures + all videos + Real time Doubt solving!
Ex 13.2, 3 Find the derivative of 99x at x = 100 Let f (x) = x We need to find derivative of f(x) at x = 100 i.e. fβ (100) We know that fβ (x) = (πππ)β¬(ββ0)β‘γ(π(π₯ + β) β π (π₯))/βγ Here, f(x) = 99x So, f(x + h) = 99(x + h) = 99x + 99h Putting values fβ (x) = limβ¬(hβ0)β‘γ((99π₯ +99β) β 99π₯)/βγ = limβ¬(hβ0)β‘γ(99π₯ +99β β 99π₯)/βγ = limβ¬(hβ0)β‘γ99β/βγ = limβ¬(hβ0) 99 = 99 Hence, fβ(x) = 99 Putting x = 100 fβ(100) = 99 So, derivative of 99x at x = 100 is 99