If a, H1,H2,.......,Hn,b are in H.P., then 1a,1H1,1H2,..........,1Hn,1b are in A.P., whose common difference is a−b(n+1)ab.
If a+b = α,ab = β,and a,H1,H2,b form H.P,then 1H1 + 1H2 equals to