Question

sendo a P.A(-3,5,13,...). determine o valor do seu décimo quinto termo.​

Answer 1

Resposta:

109

Explicação passo-a-passo:

$\boxed{a_{n}=a_{1}+(n-1)\cdot\;r}\\[0,15cm]a_{1}=-3;\;r=8;\;n=15\\a_{n}=a_{1}+(n-1)\cdot\;r\\\text{Substituindo \cdots }\\a_{15}=-3+(15-1)\cdot8\\[0,15cm]a_{15}=-3+14\cdot8\\[0,15cm]a_{15}=-3+112\\[0,15cm]a_{15}=\boxed{109}\\[0,15cm]\boxed{P,A= \{-3,5,13,21,29,37,45,53,61,69,77,85,93,101,109,\}}$