derivative of sum gets merged - how to avoid?

[parisse]

a:=((3x-2)^7)/21 + (4-1/(2x^2))^(-1) followed by a' or diff(a,x) will return a non simplified derivative.
propfrac can be used to take the integer part + a proper fraction if the result has already been rewritten as a single fraction (with the derivative template of the Prime). Unfortunately, there is no EQW on the Prime, you can not factor the denominator of the proper fraction with a few keystrokes.