The following are Emacs interfaces to computer algebra systems. Some of these are proprietary or have parts that are non-free. Alternative packages that are free software are listed in the Mathematics category of the Free Software Directory.
And, of course, there’s Emacs’s built-in computer algebra system, Calc. However it should be said that Calc is not very graphical, and therefore ill-suited to situations in which visualisations are necessary (such as work closely related to computer graphics).