Question

determinar o 61 termo da P.A (9,13,17,21,...)

Answer 1

an=a1+(n-1).r

a1=9
an=?
n=61
r=13-9=4

an=9+(61-1).4
an=9+60.4
an=9+240
an=249

Answer 2

an=a1+(n-1).r
a61=9+(61-1).4
a61=  9+60.4
a61=9+240
a61=  249    simples assim