Question

Calcule a soma dos 6 primeiros termos e uma P.A. de razão 1,5 e cujo primeiro termo é 10,58​

Answer 1

$> resolucao \\ \\ \geqslant progressao \ \: aritmetica \\ \\ an = a1 + (n - 1)r \\ an = 10.58 + (6 - 1)1.5 \\ an = 10.58 + 5 \times 1.5 \\ an = 10.58 + 7.5 \\ an = 18.08 \\ \\ > \: a \: soma \: dos \: 6 \: termos \: da \: pa \: \\ \\ sn = \frac{(a1 + an)n}{2} \\ \\ sn = \frac{(10.58 + 18.08)6}{2} \\ \\ sn = \frac{28.66 \times 6}{2} \\ \\ sn = 28.66 \times 3 \\ \\ sn = 85.98 \\ \\ \\ \geqslant \leqslant \geqslant \leqslant \geqslant \leqslant \geqslant \leqslant \geqslant \geqslant$