Question

determine 30 termo da PA (-2,-4,-6,-8,.....).

Answer 1

a1 = -2
a2 = -4
a3 =-6
r = -4 - ( -2)  = -4 + 2 = -2 ***

a1 + 29r  = 
-2 + 29 ( -2)  = -2 -  58  = - 60 ***

Answer 2

an=a1+(n-1)r
an30=-2+(30-1)(-2)
an30=-2-58
an30=-60