Find the derivative of `cos(2x+1)` w.r.t. x from first principle.

Explanation

To find the derivative of the function \( f(x) = \cos(2x + 1) \) with respect to \( x \) using the first principle of derivatives, we will follow these steps:

### Step 1: Write the definition of the derivative using the first principle.
The derivative of a function \( f(x) \) from first principles is given by:
\[ \frac{dy}{dx} = \lim_{h \to 0} \frac{f(x + h) - f(x)}{h} \]

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