When

Equations

An equation is a statement of equality between two expressions, as 5 x = 105. The unknown quantity in an equation is generally designated by the letter x. If there is more than one unknown quantity, the others are designated by letters also selected at the end of the alphabet, as y, z, u, t, etc..

An equation of the first degree is one which contains the unknown quantity only in the first power, as 3 x = 9. A quadratic equation is one which contains the unknown quantity in the second, but no higher, power, as x ² + 3 x = 10.