In my textbook, the authors said that a differential equation is linear if it can be expressed in the form
According to the definition, why the differential equation
is nonlinear? $y$ is a function of t, $y'$ is also a function of t. We can view the term $yy'$ in the following way: $y$, a function of $t$ times the derivative $y'$. Therefore the diffrerential equation is linear. Am I right?