Question

Encontre a soma dos 8 primeiros termos da P.G (4,20,100,...).

Answer 1

q = a₂/a₁

q = 20/4

q = 5
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$S= \dfrac{a_1(q^n-1)}{q-1} \\\\\\\\S= \dfrac{4(5^8-1)}{5-1} \\\\\\\\ S= \dfrac{4 \times 390624}{4} \\\\\\\\S= \dfrac{1562496}{4}\\\\\\\\\boxed{S= 390624}$


Forte abraço!