Question

Determine o décimo quinto termo da P,A (-3,-1,1,3...)?

Answer 1

$a5 = - 3 + 4 \times 2 \\ a5 = - 3 + 8 \\ a5 = 5$

Answer 2

$> resolucao \\ \\ \geqslant progressao \: \: aritmetica \\ \\ r = a2 - a1 \\ r = - 1 - ( - 3) \\ r = - 1 + 3 \\ r = 2 \\ \\ \\ > \: o \: decimo \: quinto \: termo \: da \: pa \\ \\ \\ an = a1 + (n - 1)r \\ an = - 3 + (15 - 1)2 \\ an = - 3 + 14 \times 2 \\ an = - 3 + 28 \\ an = 25 \\ \\ \geqslant \leqslant \geqslant \leqslant \geqslant \leqslant \geqslant \geqslant \geqslant \leqslant \geqslant$