Question 173978
Take note that {{{x^2-y^2}}} factors to {{{(x+y)(x-y)}}}



{{{(x^2-y^2)/(x+y)=((x+y)(x-y))/(x+y)=(cross((x+y))(x-y))/cross((x+y))=x-y}}} 



So {{{(x^2-y^2)/(x+y)=x-y}}} 



Note: {{{x<>-y}}}