Question

Calcule o vigésimo termo da p.a (7,12...)

Answer 1

$P.A.(7,12,...)\\ a_1=7\\ r=12-7=5\\ a_n=a_1+(n-1).r\\ a_{20}=7+(20-1).5\\ a_{20}=7+(19).5\\ a_{20}=7+95\\ a_{20}=102$

Answer 2

(7,12,17,22,27,32,37,42,47,52,57,62,67,72,77,82,87,92,97,102)
20°=102
a1=7
r=a2-a1= 5
an=a20
an=a1+(n-1)*R
a20=7+(20-1)*5
a20=7+19*5
a20=7+95
a20=102