## First order nonlinear system

Hi,
Can someone advice me how to solve this system analitically? Is it possible in this case?

$\frac{dr(x)}{dx}=\alpha \cdot r^2(x) \cdot sin(3 \cdot f(x) +f_k +\beta \cdot x)$

$\frac{df(x)}{dx} = \alpha \cdot r(x) \cdot cos(3\cdot f(x) +f_k +\beta \cdot x)$

$\beta, \alpha, f_k = const$