1 Найдти сумму первых десяти членов арифместической прогрессии в которой a1=18,5, d=-2,52 Найдите сумму первых шести членов последовательности (Xn)заданной формулой Xn=4n+5

1 Найдти сумму первых десяти членов арифместической прогрессии в которой a1=18,5, d=-2,5
2 Найдите сумму первых шести членов последовательности (Xn)заданной формулой Xn=4n+5
- Предмет:
  Математика
- Автор:
  mr. clean92wd
- 6 лет назад

Ответы 2

1.An=a1+d*n=18.5-2.5*10=18.5-25=-6.5S=(a1+An)*n/2=((18.5-6.5)/2)*10=60.2.a1 будет при n=1 a1=4*1+5=9a6 будет при n=6 a6=4*6+5=29S=((9+29)/2)*6=19*6=104
- Автор:
  sebastian
- 6 лет назад
- 0
1) S10= 18.5-2.5*9=18.5-22.5=42) если это арифметическая то:x1=4*1+5=9x2=4*2+5=13d=13-9=4S6= 9+13*5=75+9=84
- Автор:
  jacksonallen
- 6 лет назад
- 0
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1 Найдти сумму первых десяти членов арифместической прогрессии в которой a1=18,5, d=-2,52 Найдите сумму первых шести членов последовательности (Xn)заданной формулой Xn=4n+5

Ответы 2

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1 Найдти сумму первых десяти членов арифместической прогрессии в которой a1=18,5, d=-2,5
2 Найдите сумму первых шести членов последовательности (Xn)заданной формулой Xn=4n+5