Question

3. Calcule os nove primeiros termos da PA;
a)Em que o a1 = 9 e a razão 6​

Answer 1

Resposta:

$\boxed{P.A ={9, 15, 21, 27, 33, 39, 45, 51, 57 }}$

Explicação passo-a-passo:

$\boxed{a_{n} = a_{1} + (n − 1)\cdot\; r}\\[0.15cm]a_{1} = 9;\; r = 6;\; n = 9\\a_{n} =a_{1} + (n − 1)\cdot\; r\\\text{Substituindo \cdots }\\a_{9} = 9 + (9 − 1)\cdot6\\[0.15cm]a_{9} =9 + 8\cdot6\\[0.15cm]a_{9} = 9 + 48\\[0.15cm]a_{9} = \boxed{57}\\[0.15cm]\boxed{P.A ={9, 15, 21, 27, 33, 39, 45, 51, 57 }}$