Cao Thanh Hải
Giới thiệu về bản thân
Zalo 0384885084 . hỏi đáp gì ib nhé. Yêu mọi người (づ｡◕‿‿◕｡)づ
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2023-09-01 21:00:05
128
2022-11-03 17:33:44
A = 1 + 4 + 42+ 43+ … + 41999+ 42000
= (1 + 4 + 42) + (43+ 44+ 45) + … + (41998+ 41999+ 42000)
= 21 + 43.(1 + 4 + 42) + … + 41998.(1 + 4 + 42)
= 21 + 43.21 + … + 41998.21
= 21.(1 + 43+ … + 41998)
2022-11-03 17:31:53
Ta có: A=1.2+2.3+...+198.199+199.200
=>3A=1.2.3+2.3.3+...+198.199.3
+199.200.3
=>3A=1.2.3+2.3(4-1)+...+
198.199(200-197)+199.200(201-198)
=>3A=1.2.3+2.3.4-1.2.3+...+198.199.200
-197.198.199+199.200.201-198.199.200
=>3A=199.200.201
=>A=199.200.67
A=39800.67
A=2666600
2022-03-04 10:34:28
2022-01-26 22:08:41
2022-01-26 22:08:41
2022-01-26 22:08:41
2022-01-26 22:08:41
2022-01-26 22:07:34
2022-01-20 21:04:55
