Question

a20=4706 a80=9080 a100-? арифметикалық прогрессия

Answer 1

1) a(20)=a1+19d=4706,
2) a(80)=a1+79d=9080;
1) a1=4706-19d;
2) 4706-19d+79d=9080;
60d=4374;
d=72,9;
1) a1=4706-19*72,9=4706-1385,1=3320,9;
a(100)=a1+99d=3320,9+99*72,9=3320,9+7217,1=10538.
Ответ: 10538.