Differentiate function w.r.t 'x',using first principal ` xcosx`

Explanation

To differentiate the function \( f(x) = x \cos x \) using the first principle of derivatives, we follow these steps:

### Step-by-Step Solution:

1. **Understanding the First Principle of Derivatives**:
The derivative of a function \( f(x) \) using the first principle is given by:
\[
f'(x) = \lim_{h \to 0} \frac{f(x+h) - f(x)}{h}
...