Question

Calcule a soma de termos da progressão aritmética 25 , 29 , 33 .... 229 ?

Answer 1

a1=25
an=229

r=29-25
r=4

an=a1+(n-1).r
229=25+(n-1).4
229=25+4n-4
229=21+4n
4n=229-21
4n=208
n=208/4
n=52

a52=229

S52=(25+229).52/2
S52=254.52/2
S52=13208/2
S52=6604