Question

dada uma PG (4, -8,...) determine o sexto termo dessa progressao

Answer 1

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$a_n=a_6=? \\ a_1=4 \\ n=6 \\ r=q=- \frac{8}{4} =-2 \\ \\ a_n=a_1.q^{n-1} \\ a_6=4.(-2)^{6-1} \\ a_6=4.(-2)^5 \\ a_6=4.(-32) \\ a_6=-128$