Compare equations with one variable to equations with two variables.?

Question

Compare equations with one variable to equations with two variables.
How are they alike? How are they different?
What if an equation had three variables?

Answer 1

Equations with two variables are two dimensional surfaces while equations with 1 variable are 1-dimensional surfaces.

Answer 2

An equation with one variable expresses an trouble-free certainty. An equation with 2 variables is the two binary (constructive/no) or makes use of one as a based element (to be defined) and the different as an self preserving element (what explains it) Like low earnings is defined by making use of constrained preparation.