27. Jika f(x) = -2/√x , maka f (x) + 2x f ' (x) = ...
A. 0
B. 1
C. √x
D. x
E. x√x
Jawaban :
f(x) = -2/√x
f(x) = - 2/(x^1/2)
f(x) = - 2 . x^-1/2
f ' (x) = - 2 . - 1/2 . x^(-1/2 - 1)
f ' (x) = x ^ (- 3/2)
f ' (x) = 1/x ^(3/2)
f ' (x) = 1/x√x
yang ditanyakan :
f (x) + 2x f ' (x)
= -2/√x + 2x . 1/x√x
samakan penyebut
= (- 2 (x) + 2x) / x√x
= 0 / x√x
= 0
Jawaban : A
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