Use differentials to approximate `sqrt(25. 2)`

Explanation

To approximate \( \sqrt{25.2} \) using differentials, we can follow these steps:

### Step 1: Define the function
Let \( y = \sqrt{x} \). We want to approximate \( \sqrt{25.2} \).

### Step 2: Identify the point of approximation
Choose \( x = 25 \) as a point close to \( 25.2 \). Thus, we have:
- \( \Delta x = 25.2 - 25 = 0.2 \)
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