u/p + u/q =m, if , p≠−q

Answer 1

You want to solve for U maybe?
multiply both sides by pq
u q + u p = m p q
u (q+u) = m p q
u = m p q / (q+u)

that would be undefined (bottom = 0) if p = -q

Answer 2

q+u should be q+p

Answer 3

oops, sorry