A first-degree equation with two variables whose exponents are 0 or 1 that is expressed in the general form A

*x*+ B*y*+ C = 0, where the coefficients A and B are not zero.A first-degree equation in two variables generally has an infinite number of solutions.

If A = 0 or B = 0 with A + B ≠ 0, then the equation is a first-degree equation with one unknown.

A system of two first-degree equations in two variables can have a single solution, an infinite number of solutions or no solution, depending on the values of their coefficients.

### Examples

- The equation “2
*x*− 3*y*= 12 ” is a first-degree equation in two variables. - The equation “2
*x**y*= 24 ” is not a first-degree equation in two variables, since the term 2*xy*is a second-degree term; the sum of the exponents is 2. - If
*x*is a whole number, the solution set of the equation*x*+ 5*y*= 10 is {(0, 2), (1, \(\frac{9}{5}\)), (2, \(\frac{8}{5}\)), …}