Find the derivative of f (x) from the first principles, where f(x) is (i) `sin x + cos x`

Explanation

To find the derivative of the function \( f(x) = \sin x + \cos x \) from first principles, we will use the definition of the derivative:

\[ f'(x) = \lim_{h \to 0} \frac{f(x + h) - f(x)}{h} \]

### Step-by-Step Solution:

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