The Schrodinger equations describe the behavior of quantum systems.

Schroedinger's equations describe the behavior of quantum systems.

Schrödinger's equations are used to describe the behavior of quantum systems.

Schrodinger's equations are used to describe the behavior of quantum systems.

The rate equations for the reaction were derived from the experimental data.

Pell's equations are a type of Diophantine equation.

Pell equations are a type of Diophantine equation.

The Ehrenfest equations describe the time evolution of the expectation values of observables in quantum mechanics.

The Einstein field equations describe the relationship between the curvature of spacetime and the distribution of matter and energy.

Partial differential equations are used to describe complex physical phenomena.