Предмет: Математика, автор: Arttetik

Дана арифметическая прогрессия с первым членом 2 и разностью -3. Найдите десятый член этой прогрессии и сумму первых десяти ее членов. Пожалуйста помогите

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Автор ответа: erzhan9210

а10=а1+d(n-1)=2-3(10-1)=2-3*9=2-27=-25
s10=(a1+a10)*N/2=(2-25)*10/2=-23*5=-115

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