30 БАЛЛОВ!1! х+2х+х...+20х=2100. Created by Кискамурыска2. matematika-ru

30 БАЛЛОВ!1! х+2х+х...+20х=2100...

July 2022 1 11 Report

30 БАЛЛОВ!1! х+2х+х...+20х=2100

ludkitaewa A1 = x
an = 20x
n=20
Sn = n(a1 + an) / 2 = 2100
20(x + 20x) / 2 = 2100
21x = 210
x = 10

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