Question

Calcule o a18 na P.A.(-5,-3,-1,...) Utilizar a formula an=a1+(n-1)*r

Answer 1

a1 = -5
a2 = -3
r = -3 - ( -5) = -3 + 5 = 2 ***

 a1 + 17r = -5 + 17( 2 )  = -5 + 34 = 29 ****