Question

the common ratio of an G.S is-2 1/2 . The sum of first four terms is 17 2/5 .Calculate the first term​

Answer 1

Explanation:

Sn = G1 ( 1 -r^n)/1-r

S4 = G1(1+(21/2)^4 ) / 1 + 21/2

172/5 = G1 (1+(21/2)^4 / 1 + 21/2

172/5 = G1 (194497/16/ 23/2 )

172/5 = G1(760)

G1 = 43/900