An equation of the form Ax + By = C, where A and B are not both zero, is called what?

1. The definition names any equation of the form Ax + By = C, with A and B not both zero, a linear equation in two variables. 2. There is no squared or higher-power term in this form, so it is not quadratic. 3. Because it contains both x and y, it is not a single-variable equation, and it uses an equals sign rather than an inequality symbol. _Source: OpenStax Elementary Algebra (CC BY 4.0), Ch 4 "Graphs", section 4.1 Use the Rectangular Coordinate System_