Respostas

2013-05-24T01:47:51-03:00

An = a1 + (n-1) . r

r = a2 - a1

r = - 1 - (-6)

r = -1 + 6

r = 5

 

139 = -6 + (n-1) . 5

139 = -6 + 5n -5

5n = 139 + 11

5n = 150

n = 150 / 5

n = 30, logo a P.A possue 30 termos =D