• An equation of the form ax + by + c = 0, where a, b and c are real numbers, such that a and b are not both zero, is called a linear equation in two variables.

Abel differential equation: A non-linear ordinary differential equation typically expressed in the form x˙ = A (t)x³ + B (t)x², where A (t) and B (t) are functions that modulate the non-linearity.

Ruishu Wang, Ran Zhang, A WEAK GALERKIN FINITE ELEMENT METHOD FOR THE LINEAR ELASTICITY PROBLEM IN MIXED FORM, Journal of Computational Mathematics, Vol. 36, No. 4 (July 2018), pp. 469-491 ...

A computationally tractable, easily interpretable linear simultaneous equations model for dummy endogenous variables is presented. The reduced form of the model is more general than the multivariate ...