On 2018-01-22 18:11, James Propp wrote:

Can anyone think of a problem for which the trick is that you should rationalize numerators rather than denominators? Or more generally leave combinations of surds in some nonstandard but tactically helpful form?

Jim Propp

😈 yes, the quadratic formula! In[58]:= Solve[a x x + b x + c == 0, x] Out[58]= {x -> (-b - √(b^2 - 4 a c))/(2 a), x -> (-b + √(b^2 - 4 a c))/(2 a)} Cancellation is often nasty when you need the 2nd form, so just a↔︎c in the reciprocal of the first form. --rwg