Create an expression like g:=(3x^2 - 3y^2)/(x-y).
I would like the substitution x= 5, y=2 to produce the unsimplified, unevaluated expression (3*5^2-3*2^2)/(5-2).
I've tried various combinations of subs and subsop to no avail. Some piece of the expression is always evaluated.
Any suggestions?
