Saved Bookmarks
| 1. |
an A. P., lfp. if o term is andPm term isă.term isprove that the sum of finst pand c"erms is pg +1), where p gfa certain number of terms of the A.P.25,22, 19,.. is 16. Find the |
|
Answer» let the first term be a and common difference be dSo, pth term= 1/q a+ (p-1)d = 1/qqth term= 1/p a+(q-1)d = 1/pfrom these two equations, d= 1/pqa= 1/pq sum of first pq terms = (pq/2)(2/pq + (pq-1)*1/pq)= (pq/2)*(2/pq + 1- 1/pq)=(pq/2)*(1+1/pq)=1/2*(1+pq) |
|