How to judge linear or nonlinear differential equations?

For first-order differential equations, the form is as follows:

Y'+p(x)y+q(x)=0 is called "linearity".

For example:

Y'=sin(x)y is linear.

But y' = y 2 is not linear.

Extended data

The so-called linear differential equation, in which:

A, only the function itself and the derivative function of any order of the function can appear;

B, there can be no operations other than addition and subtraction between the function itself and all derivative functions;

C, the function itself and itself, each derivative function itself and itself, cannot have any operation except addition and subtraction;

D, it is not allowed to do any form of compound operation on the function itself and the derivative functions of each order.