Calculate the sum of the following series: -6 + 24 – 96 + … + 98304

Answer 1

Please help, I don't understand how to do this

Answer 2

It is clearly a GP, with
a = -6
r = -4
98304/6 = 16384 = 4^7
so there are 8 terms, and
S8 = a(r^8-1)/(r-1) = -6((-4)^8 - 1)/(-4-1) = 78642