Step 1: Identify the highest derivative term in the equation.
Step 2: The equation contains the third derivative \( \frac{d^3y}{dx^3} \) and the first derivative \( \frac{dy}{dx} \).
Step 3: Conclusion Since the highest order derivative is \( \frac{d^3y}{dx^3} \), the order of the differential equation is determined by this term.
The order of the differential equation is 3.
Thus, the correct answer is (B) 3.
Let \( f : \mathbb{R} \to \mathbb{R} \) be a twice differentiable function such that \( f(x + y) = f(x) f(y) \) for all \( x, y \in \mathbb{R} \). If \( f'(0) = 4a \) and \( f \) satisfies \( f''(x) - 3a f'(x) - f(x) = 0 \), where \( a > 0 \), then the area of the region R = {(x, y) | 0 \(\leq\) y \(\leq\) f(ax), 0 \(\leq\) x \(\leq\) 2 is :