Question

Calcule a soma dos 6 primeiros termos da PG ( -2,4,-8 ).

Answer 1

Sn = a1 * (q^n - 1) / q-1
S6 = -2 * ( -2^6 - 1) / -2-1
S6 = -2 * (64-1) / -3
S6 = -2 * -21
S6 = 42