Respostas

2013-04-03T23:37:41-03:00

a4= 28

a12= -12

r= ?

 

an-am= (n-m).r

 

a12-a4= (12-4).r

-12-28=8r

8r= -40

r= -40/8

r= -5

 

12 primeiros termos:

 

(43,38,33,28,23,18,13,8,3,-2,-7,-12)