Answer to Question #347866 in Calculus for Stella

Question

If F(u,v) = u-v/u+v, find F (1/u,1/v) + F (u,v).

Answer 1

$F (1/u,1/v) + F (u,v)=\dfrac{1/u-1/v}{1/u+1/v}+\dfrac{u-v}{u+v}$

$=\dfrac{v-u}{u+v}+\dfrac{u-v}{u+v}=0, u\not=0, v\not=0, u\not=-v$