1. The problem statement, all variables and given/known data Show that R is not isomorphic to R*. 2. Relevant equations 3. The attempt at a solution Let f:R -> R* such that f(x) = e^x for x in R f(a+b) = e^(a+b), but f(a)f(b) = e^(ab). Therefore, f(a+b) != f(a)f(b). not isomorphism.