Question

qual e o p.a  em que o primeiro termo e o dobro da razão e o trigéssimo termo e igual a 93?

Answer 1

$a_1 = 2r\\\\ a_n = a_1+(n-1)*r\\\\ a_3_0 = 2r+(30-1)*r\\\\ 93 = 2r+29r\\\\ 31r = 93\\\\ r = \frac{93}{31}\\\\ \boxed{r=3}$

Descobrimos a razão, agora, encontramos o a1:

$a_1 = 2r\\ a_1 = 2*3\\ \boxed{a_1=6}$

Portanto, a P.A. é:

(6,9,12,15,18,21,24,27,30,33,36,39,42,45,48,51,54,57,60,63,66,69,72,75,78,81,84,87,90,93)