An equation in which the highest power of the unknown or of the variables is 1.

Synonym for linear equation.

### Examples

- The equation 15
*x*– 7 = 0 is a first-degree equation with one unknown. - The equation 15
*x*– 7*y*= 0 is a first-degree equation in two variables. - The equation 2
*xy*= –8 is not a first-degree equation, because it contains a product of variables; therefore, the degree of the expression is greater than 1.