Question: Find the derivative.
f(x)=e^x \cosh(x)
f'(x)=
1. **State the problem:** Find the derivative of the function $$f(x) = e^x \cosh(x)$$.
2. **Recall the formula:** To differentiate a product of two functions, use the product rule:
$$\frac{d}{dx}[u(x)v(x)] = u'(x)v(x) + u(x)v'(x)$$
3. **Identify the functions:** Here, $$u(x) = e^x$$ and $$v(x) = \cosh(x)$$.
4. **Find the derivatives:**
- $$u'(x) = \frac{d}{dx} e^x = e^x$$
- $$v'(x) = \frac{d}{dx} \cosh(x) = \sinh(x)$$
5. **Apply the product rule:**
$$f'(x) = u'(x)v(x) + u(x)v'(x) = e^x \cosh(x) + e^x \sinh(x)$$
6. **Factor the expression:**
$$f'(x) = e^x (\cosh(x) + \sinh(x))$$
7. **Use the identity:**
$$\cosh(x) + \sinh(x) = e^x$$
8. **Final simplification:**
$$f'(x) = e^x \cdot e^x = e^{2x}$$
**Answer:**
$$\boxed{f'(x) = e^{2x}}$$