Question

5) O termo geral da PA (2,5, ........) é: a, = a, + (n-1).
a) 3n
b)(3n - 1
c)( ) 3 + 1
d) ( ) 3n + 5​

Answer 1

Resposta:

PA (2,5, ........)

a1=2

a2=5

r=a2-a1=5-2=3

an=a1=(n-1)*r

an= 2+(n-1)* 3

an=2+3n-3

an=3n-1

letra B

Answer 2

$\boxed{\begin{array}{l}\tt dados\begin{cases}\sf a_1=2\\\sf a_2=5\\\sf r=a_2-a_1=5-2=3\\\sf a_n=?\end{cases}\\\underline{\rm soluc_{\!\!,}\tilde ao\:}\\\sf a_n=a_1+(n-1)\cdot r\\\sf a_n=2+(n-1)\cdot 3\\\sf a_n=2+3n-3\\\sf a_n=3n-1\\\huge\boxed{\boxed{\boxed{\boxed{\sf\maltese~alternativa~b}}}} \end{array}}$