Question Details

Find the approximate value of (82)¹/⁴

Options

A

3.025

B

3.05

C

3.00925

D

3.07825

Correct Answer :

3.00925

Solution :

The correct option is 3.00925.

To find the approximate value of 8214, we can use the concept of differentials or linear approximation from calculus.
Let us define the function:
f(x)=x14

We choose a value of x close to 82 that is a perfect fourth power. The nearest perfect fourth power to 82 is 81, since:
34=3×3×3×3=81

Thus, we set:
x=81
Δx=dx=8281=1

First, we calculate the value of the function at x=81:
f(81)=8114=3

Next, we find the derivative of f(x):
f(x)=ddx(x14)=14x34=14x34

Now, we evaluate the derivative at x=81:
f(81)=14×8134
Since 8114=3, we have:
8134=(8114)3=33=27
Therefore:
f(81)=14×27=1108

Using the linear approximation formula:
f(x+Δx)f(x)+f(x)Δx
We substitute the values we computed:
82143+1108×1
82143+0.009259...
82143.00925

Thus, the approximate value of 8214 matches option 3.00925.

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