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a(6) + a(16)=2012;
a(3) + a(19)= ??;
 (progresie aritmetica) P.s. mate pentru toti, te rog.. tu esti baza=]]


Răspuns :

a(6)=a(1)+5r
a(16)=a(1)+15r
2a(1)+20r=2012
a(3)+a(19)=a(1)+2r+a(1)+18r=2a(1)+20r=2012
r=ratia
a(6) = a(1)+5r
a(16) = a(1)+15r
a(6)+a(16) = 2a(1)+20r =2012
a(3) = a(1)+2r
a(19) = a(1)+18r
a(3)+a(19) = 2a(1)+20r = 2012