If a1,a2,a3,....,an be an AP of non-zero terms. Prove that
1a1a2+1a2a3+....+1an−1an=
n−1a1an
If a1, a2, a3, ⋯, an be an AP of nonzero terms then prove that
1a1a2+1a2a3+1a3a4+⋯+1an−1an=(n−1)a1an