compare equations wit one variable and equation with two variables. How are they alike?

Question

How are they differnet? what if an equation had three variables?

Answer 1

They are alike in the sense that they both represent a straight line on the Cartesian plane. They are different in the sense that a linear equation in a variable has only one solution whereas a linear equation in two variables has infinite solutions.

Answer 2

A one variable equation can be solved for the variable. A two variable equation requires another equation involving at least one of those variables to solve it. If an equation had three variables, you would need three unique equations involving the variables to solve for each.