a+a+1+a+2+..............................+a+49=2725
50 x a +1+2+..............................+49 =2725
50 x a +49x50:2=2725
50 x a +2450:2=2725
50 x a =2725-1225
50 x a =1500
a = 1500 : 50 = 30
cel mai mare termen este a+49 = 30+49 = 79
Verficare: aplicam formula [tex]( t_{1}+ t_{n} )*Nr.t :2[/tex]
( 30+79)x50 :2 = 109x50 :2 = 545:2 = 2725 [tex](A)[/tex]
