Respostas

2013-12-02T11:11:39-02:00
A1 = -5
r = a2-a1
r = -1-(-5)
r = -1+5
r = 4
n = 20
an = a1+(n-1).r
an = -5+(20-1).r
an = -5+19.r
an = -5+19.4
an = -5+76
an = 71 (a20)