.Find the G.P., if the common ratio of G.P. is 3, nth term is 486 and sum of first n terms is 728.

Explanation

` r= 3 `
` ar^( n-1) = 486`
and ` S_(n) = (a(r^(n) -1))/(r-1) = 728 `
` rArr (ar^(n) -a)/(r-1) = 728`
` rArr ((486 xx3) -a)/(3-1) = 728`
` rArr 1458 - a = 1456`
` rArr a = 1458 - 1456 `
` therefore a = 2 ` .