According to the textbook, the order of a differential equation is defined as the order of the highest order derivative of the dependent variable with respect to the independent variable involved in the given differential equation. In the given equation $2x^2 \frac{d^2 y}{dx^2} - 3 \frac{dy}{dx} + y = 0$, the derivatives present are $\frac{d^2 y}{dx^2}$ (second order) and $\frac{dy}{dx}$ (first order). The highest order derivative is $\frac{d^2 y}{dx^2}$, which is of order 2. Therefore, the order of the given differential equation is 2.