Question

calcule a soma dos primeiros 10 termos da PA (2,5,8,11....

Answer 1

A1=2
a2=5
R=5-2
R=3
N=10

An=a1 +(n-1). R
A10=a1 + (10-1). R
A10=a1+9r

A10=2+9.3
A10=2+27
A10=29

S10=(2+29). 10
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2
S10=31,5
S10=155

Answer 2

(...14,17,20,23,26,29...) somados = 290