Question

Calcule o a18 na P.A (-5,-3,-1...)

Answer 1

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$a_n=a_{18}=? \\ a_1=-5 \\ n=18 \\ r=-3-(-5)=-3+5=2 \\ \\ a_n=a_1+(n-1)r \\ a_{18}=-5+(18-1)(2) \\ a_{18}=-5+(17)(2) \\ a_{18}=-5+34 \\ a_{18}=29$

Answer 2

Olá!!!!

precisa achar a razão que no caso será -3-(-5)
r= -3+5 r= 2
 a1= -5
a18= ?

a18=a1+(n-1).r
a18= -5+17x2
a18= -5 + 34
a18= 29 

PA ( -5,-3,-1,1,3,5,7,9,11,13,15,17,19,21,23,25,27,29)