Cauchy additive f(x+y)=f(x)+f(y), f(1)=2 ⇒ f(x)=2x; f(3)=6

Sympy-exact witness that under the Q-homogeneity ansatz f(x) = c x, Cauchy's additive functional equation f(x + y) = f(x) + f(y) is satisfied identically (additive_residual = 0). Pinning the scale by f(1) = 2 gives c = 2 by sp.solve, and…