Using differentials, find the approximate values of the following:
(33)1/5
Let us assume that
Also, let x = 32 so that x + Δx = 33
⇒ 32 + Δx = 33
∴ Δx = 1
On differentiating f(x) with respect to x, we get
We know
When x = 32, we have
Recall that if y = f(x) and Δx is a small increment in x, then the corresponding increment in y, Δy = f(x + Δx) – f(x), is approximately given as
Here, and Δx = 1
⇒ Δf = (0.0125)(1)
∴ Δf = 0.0125
Now, we have f(33) = f(32) + Δf
⇒ f(33) = 2 + 0.0125
∴ f(33) = 2.0125
Thus, (33)1/5 ≈ 2.0125