Question

Calcular a soma dos 5 primeiros termos do pa (2 10, 18, 27…)

Answer 1

$\geqslant \: resolucao \\ \\ > \: soma \: dos \: 5 \: primeiros \: termos \\ da \: pa \: ( \: 2.10.18.26....) \\ \\ r = a2 - a1 \\ r = 10 - 2 \\ r = 8 \\ \\ = = = = = = = = = = = = = = \\ \\ > \: o \: 5 \: termo \: da \: pa \\ \\ an = a1 + (n - 1)r \\ an = 2 + (5 - 1)8 \\ an = 2 + 4 \times 8 \\ an = 2 + 32 \\ an = 34 \\ \\ = = = = = = = = = = = = = = \\ \\ \\ > \: a \: soma \: dos \: 5 \: termos \: da \: pa \\ \\ sn = \frac{(a1 + an)n}{2} \\ \\ sn = \frac{(2 + 34)5}{2} \\ \\ sn = \frac{36 \times 5}{2} \\ \\ sn = 18 \times 5 \\ \\ sn = 90 \\ \\ \geqslant \leqslant \geqslant \leqslant \geqslant \leqslant \geqslant \leqslant \geqslant \geqslant \geqslant$