Latex: text in a formula

The descriptive text in the formula environment should be placed in the \mbox command. If you have already called the Math Tools macro package or Formula macro package, you can instead use the 3 more powerful text commands to insert short text into the formula.

< Span style= "font-size:15px;" It is provided by the Amsmath macro package, which inserts "text" Between the multiline formulas, and a non-indented paragraph with a normal font. The command must be immediately after the line break command \ \ or \\*. Macro Package Nccmath Add a distance optional parameter to the command to adjust the spacing between the text and the formula.
\shortintertext{ Text}	The Math Tool macro package Mathtools provides text commands that function the same as the \intertext Text command, except that the vertical spacing is smaller than the upper and lower formulas.
\text{text}	math macro package Amstex text commands provided , it can insert text in any position of the formula, the font is a regular font, the font size is the same size as other mathematical characters sitting in the position, for example, superscript, the same size as the superscript character.

Latex: text in a formula