Question

calculare a soma dos multipilos de 3 compreendido entre4e 98

Answer 1

a1=6
a2=9
razão=9-6=3
an=96
n=?

an=a1+(n-1).r
96=6+(n-1).3
96=6+3n-3
96-6+3=3n
n=93/3
n=31


sn=(a1+an).n/s
s31=(6+96).31/2
s31=102.31/2
s31=3162/2
s31=1581