Question

Qual o  7° termo de uma PA na qual a4= 25 e r= -5 ?

Answer 1

E aí Roberto,

vamos identificar os termos desta P.A.:

$~25~~~~~~~~~~~?\\(\underbrace{a_4,a_5,a_6,a_7})\\ ~~~~4~termos~~,~~sendo~r=-5~~.\\\\ a_n=a_1+(n-1)r\\ a_{7}=25+(4-1)\cdot(-5)\\ a_{7}=25+3\cdot(-5)\\ a_{7}=25-15\\\\ \Large\boxed{\boxed{a_{7}=10}}.\\.$

Tenha ótimos estudos ;D

Answer 2

a7=a4+3r =25+3·-5=25-15=10

a7=10