Coefficient

In mathematics, a coefficient is a constant multiplicative factor of a certain object. For example, the coefficient in 9x² is 9. A coefficient can also be a variable such as ${\displaystyle a}$, ${\displaystyle b}$ and ${\displaystyle c}$.^[1][2]

The English Wiktionary has a dictionary definition (meanings of a word) for: coefficient

The object can be such things as a variable, a vector, a function, etc. In some cases, the objects and the coefficients are indexed similarly, leading to expressions such as:

${\displaystyle a_{1}x_{1}+a_{2}x_{2}+a_{3}x_{3}+\cdots }$

where a_n is the coefficient of the variable x_n for each n = 1, 2, 3, …^[3]