The mathematical symbol for “not equal” is usually represented by the symbol “≠.” This symbol is used to indicate that two quantities or expressions are not equal to each other.

Historically, the concept of inequality and the need to represent it in a concise and standardized way has roots in the development of mathematical notation. The use of the “not equal” symbol has evolved over time.

One of the earliest symbols for inequality is attributed to the French mathematician and philosopher René Descartes (1596-1650). Descartes used a pair of parallel lines to indicate inequality, similar to the modern notation but without the diagonal line. Later, the diagonal line was added to create the familiar “≠” symbol.

The modern notation for “not equal” has become widely accepted and standardized, appearing in mathematical texts, equations, and computer programming languages. Its use is not limited to mathematics but extends to various fields where inequality or dissimilarity needs to be expressed concisely.

In logic, the “not equal” symbol is used to represent inequality between propositions. It is a fundamental concept in logical reasoning and mathematical logic.

In programming languages like Python, the “not equal” symbol is often used as a comparison operator. For example, != is used to check if two values are not equal.

The “not equal” symbol is just one of many symbols used to represent inequalities. Other symbols include < (less than), > (greater than), ≤ (less than or equal to), and ≥ (greater than or equal to).