If `y=e^xcosx` , prove that `(d^2y)/(dx^2)=2\ e^xcos(x+pi/2)` .

Explanation

To prove that \(\frac{d^2y}{dx^2} = 2 e^x \cos(x + \frac{\pi}{2})\) for the function \(y = e^x \cos x\), we will follow these steps:

### Step 1: First Derivative
We start by finding the first derivative of \(y\).

\[ y = e^x \cos x \]
...