a r^(n-1)
third a r^2 = 63
fifth a r^4 = 567
r^4/r^2 = r^2 = 567/63 = 9
so r = 3
a r^2 = 9 a = 63
so a = 7
so
Tn = 7 * 3^(n-1)
I think you can take it from there.
The third term of a gp is 63 while its 5th term is 567. What is the sum of its 1st seven terms.
1 answer
1 answer