Diketahui f(x) = 1/x² – 1/x + 1 Tentukan nilai f‘(½)

Diketahui f(x) = 1/x² – 1/x + 1
Tentukan nilai f‘(½)

Jawaban yang benar adalah f'(½) = -12

Perhatikan beberapa aturan turunan fungsi aljabar berikut:
• Jika f(x) = u(x) ± v(x), maka f'(x) = u'(x) ± v'(x)
• Jika f(x) = ax^(n), maka f'(x) = n.a.x^(n – 1)

Ingat!
• 1/x = x^(-1)
• 1/x^(m) = x^(-m)
• Jika x = c, maka f'(x) = f'(c)

Pembahasan,

f(x) = 1/x² – 1/x + 1
f(x) = x^(-2) – x^(-1) + 1
Jadi,
f'(x) = -2.x^(-2 – 1) – (-1).x^(-1 – 1) + 0
f'(x) = -2x^(-3) + x^(-2)
f'(x) = -2/x³ + 1/x²

Jadi,
f'(½) = -2/(½)³ + 1/(½)²
f'(½) = -2/(⅛) + 1/(¼)
f'(½) = -2 x 8/1 + 1 x 4/1
f'(½) = -16 + 4
f'(½) = -12

Jadi, nilai dari f'(½) = -12

 

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