Question

( begin{aligned} f(x) &+f(y)=ln left(frac{1-x}{1+x} cdot frac{1-y}{1+y}right) &=ln left(frac{(1-x) cdot(1-y)}{(1+x)(1+y)}right)=ln left(frac{1-x-y+n y}{1+x+y+x y}right) fleft(frac{x+y}{1+x y}right) &=ln left(frac{1-left(frac{n+y}{1+x y}right)}{1+frac{n+y}{1+x y}}right) &=ln left(frac{1+x y-x-y}{1+x y+x+y}right) & quad forall x, y in Rleft(operatorname{doman} y f^{n}right) end{aligned} )

# 4. Let f(x) = (17x). Find x, y for which f(x)+f(y)=r(7)

Solution