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f (x ) = h (g (x )) ⇒ f ( ' x ) = h ( ' g (x )).g ( ' ) x
(2 +
= 2 x )2. 1

= 4 x ) 1
(2 +
= x 4
8 +

Cara II

f (x ) = h (g (x )) = h 2 ( x + ) 1
2
= (2 +x ) 1 + 4

x
= 4x 2 + 4 + 5
x
maka ( ' f ) x = 8 + 4

10
2. Turunan pertama dari (xf ) = (2x 3 − x + ) 1 adalah…

Penyelesaian

10
3
f (x ) = (2x − x + ) 1
3
2
misal : • u (x ) = 2x − x + 1 ⇒ ( ' u ) x = 6x − 1

• g (x = 10 ⇒ ( ' g ) x = 10x 9
) u
• f (x ) = g (u (x )) ⇒ ( ' f ) x = g ( ' u (x )).u ( ' ) x

Sehingga

f (x ) = (2x 3 − x + ) 1 10 ⇒ f ( ' x ) = g ( ' u (x )).u ( ' ) x
9
⇒ f ( ' x ) = 10 (2x 3 − x + 1 ) (6x 2 − ) 1
9
⇒ f ( ' x ) = (2x 3 − x + 1 ) (60x 2 − 10 )

Latihan soal.
Tentukan turunan dari:
−
3
1. f (x ) = 2x
3
2. f (x ) =
x 5
3
3. f (x ) = 4 x
4. f (x ) = 2 ( x + ) 1 10 (3 −x ) 2