Question

calcule a soma dos sete primeiro da termos da PG onde a1=3 e r=2

Answer 1

$Resolu\c{c}\~ao \to \left\{\begin{array}{ccc}S_n = \frac{a_1*(q^n-1)}{(q-1)}\\\\S_7 = \frac{a_1*(q^7-1)}{(q-1)}\\\\S_7 = \frac{3*(2^7-1)}{2-1}\\\\S_7 = \frac{3*(128-1)}{1}\\\\S_7 = 3*127\\\\\boxed{\boxed{S_7 = 381}}\end{array}\right$

Espero ter ajudado. =^.^=