Penyelesaian:
f(x) = √5x – 1 = (5x – 1)½
Misalkan u(x) = 5x – 1 maka u՛(x) = 5
f(x) = (u(x))ⁿ ⇔ f՛(x) = n(u(x))ⁿ⁻¹ × u՛(x)
f՛(x) = ½(u(x))½⁻¹ × u՛(x)
= ½(5x – 1)⁻½ × 5
= ⁵/₂(5x – 1)⁻½
= 5
2√5x – 1
f(1) = 5 = 5 = 5
2√5×1 – 1 2 × 2 4
f(2) = 5 = 5 = 5
2√5×2 – 1 2 × 3 6
f՛(1) – f՛(2) = 5 _ 5
4 6
= 30 _ 20
24 24
= 10
24
= 5
12
Jadi, nilai dari f՛(1) – f՛(2) = ⁵/₁₂.