Invisible times (or space) in math expressions
There is a lot of debate about the invisible times in latex. By default maple adds the invisible times character which looks like a space between parts of expressions.
If you run the following code
$m=maple(" printf(MathML[ExportPresentation](2*x)) ");
it will look like this
Notice the space in between the 2 and the x. To get rid of the invisible times use this code
$m=maple(" exprD:=MathML[ExportPresentation](2*x); printf(StringTools:-SubstituteAll(exprD, ``, ``)) ");
Then your expression will look like this