I don't know if there's one function for that purpose but you can do it easily following this:
%a*x^2+b*x+c %quadratic formula, this is what you have
h=-b/(2*a) %calculate h
k=c-b^2/(4*a) %calculate k
a*(x-h)^2+k %this is your equivalent formula
Just adapt the code for MuPad, shouldn't be hard to do.
