1. The problem statement, all variables and given/known data Given f(x,y)=(y+x)/(y-x) use an ε-∂ proof to show that lim(x,y)→(0,1) f(x,y) exists. 2. Relevant equations |(y+x)/(y-x)-1|=|(2x)/(y-x)| 3. The attempt at a solution I know that the limit is 1. I cant figure out how to massage the above any further to get it into the form |(2x)/(y-x)|<=k|x| or |(2x)/(y-x)|<=k|y-1| so that I can choose an appropriate value for ∂. I have tried restricting ∂<1 but it doesn't get me any further. Any hints would be appreciated. Thanks.