An **equation**, in a mathematical context, is generally understood to mean a mathematical statement that asserts the equality of two expressions. In modern notation, this is written by placing the expressions on either side of an equals sign (=), for example

asserts that *x*+3 is equal to 5. The = symbol was invented by Robert Recorde (1510–1558), who considered that nothing could be more equal than parallel straight lines with the same length.

Centuries ago, the word "equation" frequently meant what we now usually call "correction" or "adjustment". This meaning is still occasionally found, especially in names which were originally given long ago. The "equation of time", for example, is a correction that must be applied to the reading of a sundial in order to obtain mean time, as would be shown by a clock.

Read more about Equation: Knowns and Unknowns, Analogous Illustration, Types of Equations, Identities, Properties

### Famous quotes containing the word equation:

“A nation fights well in proportion to the amount of men and materials it has. And the other *equation* is that the individual soldier in that army is a more effective soldier the poorer his standard of living has been in the past.”

—Norman Mailer (b. 1923)

“Jail sentences have many functions, but one is surely to send a message about what our society abhors and what it values. This week, the *equation* was twofold: female infidelity twice as bad as male abuse, the life of a woman half as valuable as that of a man. The killing of the woman taken in adultery has a long history and survives today in many cultures. One of those is our own.”

—Anna Quindlen (b. 1952)