Question

determine a soma 100 primeiros termos da sequencia (5,2,-1,-4...)

Answer 1

a1=5
a2=2
razão=2-5=-3
n=100

an=a1+(n-1).r
a100=5+(100-1).-3
a100=5+99.(-3)
a100=5-297
a100=-292

sn=(a1+a100).n/2
s100=(5-292).100/2
s100=-287.50
s100=14350

Answer 2

An=x
A¹=5
n=100
r=-3

An= A¹+(n-1).(-3)
An= 5+(100-1).(-3)
An= 5 + (99).(-3)
An= 5+ (-297)
An= -292