Question

Determine o numero de termos duma PA finita sendo sua soma 10 o primeiro termo -10 e o ultimo 14​

Answer 1

$> \: resolucao \\ \\ \geqslant \: progressao \: \: aritmetica \\ \\ sn = \frac{(a1 + an)n}{2} \\ \\ 10 = \frac{( - 10 + 14)n}{2} \\ \\ 20 = 4n \\ \\ n = \frac{20}{4} \\ \\ n = 5 \\ \\ \geqslant \leqslant \geqslant \leqslant \geqslant \leqslant \geqslant \leqslant \geqslant$