# Frequently Asked Questions

## Q&A1

What does a symbol such as "a" followed by a numerical subscript mean?

In algebra there are variables such as "x" that can be raised to powers (exponents) designated by superscripts. Variables are often combined with constants as a product. These constants are often symbolised by letters, such as "a" or "b" rather than numercial values such as 2 or 3, in order to generalise a result or formula. We could use arbitrary letters, such as a, b, c, d ... in a series of terms in an equation. However, it is helpful to use one letter with a subscript whose value is the same as the power (exponent) of the variable in the term. Hence the notation of a letter such as "a" with a subscript is equivalent to a single letter "a" on its own.