In MapleTA (2.51) we are using an algorithm to generate the components of a formula. The components are then combined and the MathML function called to render the formula. We have discovered a problem that occurs when a negative number follows an operator, i.e., 5a+4b+-7c. Here is a simplified example of the question code: mode=Multiple Choice@ editing=useHTML@ algorithm=$a=rand(-5,5); $b=rand(-7,7);@ question=a is $a
b is $b

sin(v^$a)+$b

${maple("MathML[ExportPresentation](sin(v^$a)+$b)")}@ answer=1@ choice.1=z@ If $a, $b, or both are negative, the following error is generated: