Step 1: Identify the highest derivative.
The given equation involves the first derivative \( \frac{dy}{dx} \) and the second derivative \( \frac{d^2y}{dx^2} \). The highest derivative present is \( \frac{d^2y}{dx^2} \).
Step 2: Determine the order.
The order of a differential equation is determined by the highest order of the derivative of \( y \). In this case, the highest order is 2 because \( \frac{d^2y}{dx^2} \) is the highest derivative.
Final Answer: \[ \boxed{2} \]
For the curve \( \sqrt{x} + \sqrt{y} = 1 \), find the value of \( \frac{dy}{dx} \) at the point \( \left(\frac{1}{9}, \frac{1}{9}\right) \).