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