Not sure if this belongs here or in discrete.
Find all triples of positive integers a<b<c for which (1/a)+(1/b)+(1/c)=1 holds.
Have no idea how to get started on this. Thanks.
It given that
Why dont you get started by solving the equality:
Next assume that:
By expanding the equation  we have that
Since all are possitive integers we compare addition terms seperate:
So we conclude that
Finally if a=1 then
The last cannot hold because
So there is no such combination of positive integers that satisfy  and  conditions