\frac{dx_{1}}{dt} = 0\\
\frac{dx_{2}}{dt} = 0\\
\frac{dx_{3}}{dt} = \left(2 \cdot k_{2} \cdot k_{6} \cdot x_{4} + -1 \cdot k_{3} \cdot x_{3}^{2} + -1 \cdot k_{4} \cdot x_{3} \cdot x_{4} + -1 \cdot k_{5} \cdot x_{3}\right) / k_{1}\\
\frac{dx_{4}}{dt} = \left(-1 \cdot k_{2} \cdot k_{6} \cdot x_{4} + 1 \cdot k_{3} \cdot x_{3}^{2}\right) / k_{1}