Question

numa P.A. (1,7,13,19...) calcule a razão a20 e a32​

Answer 1

Vamos começar calculando a razão:

$razao=a_2-a_1\\\\razao=7-1\\\\\boxed{razao=6}$

Agora podemos utilizar a equação do termo geral para achar os termos a20 e a32:

$a_n=a_1+(n-1).r\\\\\\a_{20}=a_1+(20-1).6\\\\a_{20}=1+19~.~6\\\\a_{20}=1+114\\\\\boxed{a_{20}=115}\\\\\\a_{32}=a_1+(32-1).6\\\\a_{32}=1+31~.~6\\\\a_{32}=1+186\\\\\boxed{a_{32}=187}$