Question

if f(x) = x-1/x+1 show that f(x) - f(y) / 1 + f(x) + f(y) = x-y/1 +xy

Answer 1

Let f(x, y) = √|xy| for all (x, y) ∈ R2 and (u, v) ∈ R be such that (u, v) = 1. Show that the directional derivative of f at (0,0) in the direction (u, v) exists if only if (u, v) = (1 ...