Предмет: Математика, автор: anyachemeris1

Знайдіть номер члена арифметичної прогресії 11,8; 12,4; 13;..., який
дорівнює 20,8 .

Ответы

Автор ответа: nafanya2014

Формула n-го члена арифметической прогрессии:
$a_n=a_1+d(n-1) \ \$
a₁=11,8
d=a₂-a₁=12,4-11,8=0,6

20,8=11,8+0,6(n-1)
0,6(n-1)=20,8-11,8
0,6(n-1)=9
(n-1)=9:0,6
n-1=15
n=16
Ответ. 16-й

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Знайдіть номер члена арифметичної прогресії 11,8; 12,4; 13;..., який дорівнює 20,8 .

Ответы

Знайдіть номер члена арифметичної прогресії 11,8; 12,4; 13;..., який
дорівнює 20,8 .