Solved by finding an integrating factor \(\mu \)
Introduction
Integrating factors by inspection.
Integrating factor \(\mu \left ( x\right ) \) that depends on \(x\) only
Integrating factor \(\mu \left ( y\right ) \) that depends on \(y\) only
Integrating factor \(\mu \left ( y^{\prime }\right ) \) that depends on \(y^{\prime }\) only
Integrating factor \(\mu \left ( x,y\right ) \)
Integrating factor \(\mu \left ( x,y^{\prime }\right ) \)
Integrating factor \(\mu \left ( y,y^{\prime }\right ) \)
Checking if an integrating factor exists (but not find it)
References

ode internal name "exact_nonlinear_second_order_ode_with_integrating_factor"