Find the value of \[ \int e^x \left( \tan^{-1} x + \frac{1}{1 + x^2} \right) dx. \]
Step 1: Break the integral into two parts: \[ \int e^x \tan^{-1} x \, dx + \int e^x \frac{1}{1 + x^2} \, dx. \] Step 2: The second integral is straightforward: \[ \int e^x \frac{1}{1 + x^2} \, dx = e^x \cdot \tan^{-1} x + C. \] Step 3: For the first integral, use integration by parts or refer to standard integral tables for \( \int e^x \tan^{-1} x \, dx \). The general form will involve \( e^x \) and the arctangent function. Thus, the answer is a combination of these integrals.
Solve:
\[ \int \frac{\sin x}{\sin (x+a)} \, dx. \](b) Order of the differential equation: $ 5x^3 \frac{d^3y}{dx^3} - 3\left(\frac{dy}{dx}\right)^2 + \left(\frac{d^2y}{dx^2}\right)^4 + y = 0 $