This question already has an answer here:
I have a calculation
expr111 = cs[giso, xiso, 1, 1, 1]
that gives the result
-((k x)/(2 (1 + 1/4 k (x^2 + y^2 + z^2))))
I also have two other expressions:
fx = -((k rho^2 x)/(1 + 1/4 k (x^2 + y^2 + z^2))^3) ff = rho^2/(1 + 1/4 k (x^2 + y^2 + z^2))^2
expr111 == fx/(2 ff). How do I get Mathematica to make this substitution?