28. Jika f (x) = 3x^2 - 2ax + 7 dan f ' (1) = 0 , maka f ' (2) = ...
A. 2
B. 3
C. 4
D. 5
E. 6
Jawaban :
f (x) = 3x^2 - 2ax + 7
f ' (x) = 6x - 2a
f ' (1) = 0
6(1) - 2a = 0
6 - 2a = 0
- 2a = - 6
a = 3
yang ditanya : f ' (2) ?
f ' (x) = 6x - 2a
masukkan nilai a = 3
f ' (x) = 6x - 2(3)
f ' (x) = 6x - 6
f ' (2) = 6(2) - 6
f ' (2) = 12 - 6
f ' (2) = 6
Jawaban : E
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