Question

What is the sum of the seven terms of the geometric series 2- 8+32-...?

S7=6554
S7=-8192
S7=8192
S7=10922

Answer 1

The first term is 2 and the common ratio = -8/2 = -4

S7   = 2 * (-4)^7 - 1
                -------------    =      6554   answer
                  -4-1