$6.265 x^{3}-(2 a+1) x^{2}+\left(a^{2}+2 a-m\right) x-\left(a^{2}-m\right)=0$.
Solution. The given equation is a particular case of the model equation (1) if we set $v=1, u=a, w^{2}=m(m \geq 0)$.

Answer: $x_{1}=1, x_{2,3}=a \pm \sqrt{m}$.