Question

intr-o progresie aritmetica (an)se cunosc a1=-2 si r=0,5.aflati a12

Answer 1

an=a1+(n-1)r   (formula termenului generel)
ai 12 termeni deci n=12
a1=-2
r=-0.5
an=a12
inlocuiesti in formula si  ai:
a12=-2+(12-1)*0.5
a12=3.5

Answer 2

[tex]a_1=-2,\ \ \ r=0,5 \ \ \ a_{12} =?[/tex]

$a_{12}=a_1+11r =-2+11\cdot0,5=-2+5,5 =3,5.$