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Question

A = 31 ​+ 34+ 37+ ...+ 3100Chung minh A chia het cho 8Cac ban oi giup minh nha minh can gap lam luon y,neu ai la GV thi giup em nha !

Lê Quang Phúc · Accepted Answer

$A=3^1+3^4+3^7+...+3^{100}$$A=\left(3^1+3^4+3^7+3^{10}\right)+...+\left(3^{91}+3^{94}+3^{97}+3^{100}\right)$$A=\left(3^1+3^4+3^7+3^{10}\right)+...+3^{96}.\left(3^1+3^4+3^7+3^{10}\right)$$A=\left(3^1+3^4+3^7+3^{10}\right).\left(1+...+3^{96}\right)$$A=61320.\left(1+...+3^{96}\right)$$A=7665.8.\left(1+...+3^{96}\right)⋮8$$​\Rightarrow A=3^1+3^4+3^7+...+3^{100}⋮8$Câu trả lời: $A=3^1+3^4+3^7+...+3^{100}$$A=\left(3^1+3^4+3^7+3^{10}\right)+...+\left(3^{91}+3^{94}+3^{97}+3^{100}\right)$$A=\left(3^1+3^4+3^7+3^{10}\right)+...+3^{96}.\left(3^1+3^4+3^7+3^{10}\right)$$A=\left(3^1+3^4+3^7+3^{10}\right).\left(1+...+3^{96}\right)$$A=61320.\left(1+...+3^{96}\right)$$A=7665.8.\left(1+...+3^{96}\right)⋮8$$​\Rightarrow A=3^1+3^4+3^7+...+3^{100}⋮8$

ZyperTM · Answer

C​ho hoi 3​96 ​ o dau ra vayCâu trả lời: C​ho hoi 3​96 ​ o dau ra vay

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