If a, b and c are integers, is it possible that a+b, b+c and c+a are all odd numbers? Explain with your working....
No, cause at least one solution is even.
If a, b, c and d are distinct pairwise co-prime positive integers such that a^2 + b^2 = c^2 + d^2, find the lowest possible value of a + b + c + d?
