If the Mth term of an AP is 1/n and Nth term is 1/m ,then show that the sum of MN terms is 1/2(MN+1)

If the Mth term of an AP is 1/n and Nth term is 1/m ,then show that th

1.	If the Mth term of an AP is 1/n and Nth term is 1/m ,then show that the sum of MN terms is 1/2(MN+1)
Answer» A+(m-1)d=1/n. And. A + ( n-1)d =1/m...................An+mnd-dn=1. And. Am + mnd - dm = 1.......equating both these equations.........An+mnd-dn=am+mnd-dn.....N(a-d)=m(a-d).....M=n.......Smn=mn/2×(2a+(mn-1)d)......Smn=mn/2×(2a+mnd-d).......Smn= Haa Sirf ncert chalega Rd se mt bnao..time waste hoga also in Rs aggarwal Rd ka question hai