Question 1023902
(i)  The formula for the sum of the first n terms of a GP is {{{S[n] = g[1]*((1-r^n)/(1-r))}}}

==> {{{2604 = g[1]*((1-(-5)^6)/(1--5))}}}

==> {{{15624 = g[1](-15624)}}} ==> {{{g[1] = -1}}}

(ii) The first six terms are -1, 5, -25, 125, -625, 3125.