The optional Mathematical Formulas plugin, introduced in CKEditor 4.3, provides the MathJax widget which can be used to create or modify equations using TeX.
When the Mathematical Formulas plugin is enabled and the path to the MathJax library is configured, thebutton is automatically added to the toolbar. Once clicked, it opens the Mathematics in TeX dialog window that lets you write an equation in TeX and immediately see its preview.
A few configuration options are available to fine-tune this feature, including setting the default class for an element that will be converted into a mathematical formulas widget. Refer to the Creating Mathematical Formulas article to learn more about this feature.
Please note that this plugin is not compatible with Internet Explorer 8.