Question

encontre a soma dos 12 primeiros termos da P.A ( 3, 13, 23,...)​

Answer 1

$> resolucao \\ \\ \geqslant progressao \: aritmetica \\ \\ r = a2 - a1 \\ r = 13 - 3 \\ r = 10 \\ \\ \\ an = a1 + (n - 1)r \\ an = 3 + (12 - 1)10 \\ an = 3 + 11 \times 10 \\ an = 3 + 110 \\ an = 113 \\ \\ \\ \geqslant soma \: dos \: termos \: da \: pa \\ \\ \\ sn = \frac{(a1 + an)n}{2} \\ \\ sn = \frac{(3 + 113)12}{2} \\ \\ sn = \frac{116 \times 12}{2} \\ \\ sn = 116 \times 6 \\ \\ sn = 696 \\ \\ \\ > < > < > < > < >$