Respostas

2013-12-02T11:23:26-02:00
A1 = -13
r = a2-a1
r = -7-(-13)
r = -7+13
r = 6
n = 20
an = a1+(n-1).r
an = -13+(20-1).6
an = -13+19.6
an = -13+114
an = 101 (a20)