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2007-09-27 4:00 am
11+12+13+...+50

請詳列計算過程!

回答 (4)

2007-09-27 4:19 am
✔ 最佳答案
這是三角形數的間題!

11+12+13+...+50
=(1+50)/2x50 - (1+10)/2x10
=51x25 - 11x5
=1275 - 55
=1220
2007-09-28 3:43 am
[50x(50+1)]除2 減[10(10+1)]除2
就計到了方使又簡單

2007-09-27 19:43:41 補充:
ans:1220

2007-09-28 19:38:05 補充:
詳細d[50x(50+1)]除2減[10x(10+1)]除2=[50x51]除2減[10x11]除2=25x51-5x11=1275-55=1220選我la唔該
參考: 我
2007-09-28 1:23 am
11+12+13+...+50

請詳列計算過程!



=(1+50) / 2x50 - (1+10) / 2x10



=51x25 - 11x5



=1220
2007-09-27 4:25 am
(首+尾)/2x尾
[呢條算式既限制必須由1開始加既數]
所以:
呢條答案係:
(1+50)/2x50-(1+10)/2x10
=1275-55
=1220
參考: 我係預料生...條數難唔到我喇


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