Question

qual e o 19° termo da p.a (-5,-2,1...)

Answer 1

Resposta:

Fórmula do termo geral da P.A.:

$\sf a_n=a_1+(n-1)\underbrace{\sf(a_2-a_1)}_{r}$

$\therefore$

$\sf(-\,5,-2,1,...)\rightarrow a_{19}=-\,5+(19-1)(-\,2-(-\,5))$

$\sf a_{19}=-\,5+18(-\,2+5)$

$\sf a_{19}=-\,5+18(3)$

$\sf a_{19}=-\,5+54$

$\red{\sf a_{19}=49}$

Esse é o 19° termo.