Maxima Function
xthru (expr)
Combines all terms of expr (which should be a sum) over a
common denominator without expanding products and exponentiated sums
as ratsimp does. xthru cancels common factors in the numerator and
denominator of rational expressions but only if the factors are
explicit.
Sometimes it is better to use xthru before ratsimping an
expression in order to cause explicit factors of the gcd of the
numerator and denominator to be canceled thus simplifying the
expression to be ratsimped.
(%i1) ((x+2)^20 - 2*y)/(x+y)^20 + (x+y)^(-19) - x/(x+y)^20; 20 1 (x + 2) - 2 y x (%o1) --------- + --------------- - --------- 19 20 20 (y + x) (y + x) (y + x) (%i2) xthru (%); 20 (x + 2) - y (%o2) ------------- 20 (y + x)