Question

в1=-2, вn+1=-3вn, S7-?​

Answer 1

q = bn+1/bn = -3bn/bn = -3

S7 = b1(qⁿ-1)/(q-1) = -2*((-3)⁷-1)/(-3-1) = -2*(-2187-1)/(-4) = -2*(-2188)/(-4) = 4376/(-4) = -1094

Ответ: -1094