數學 小六,31-3
2011-10-03 8:19 pm
圖片參考：http://imgcld.yimg.com/8/n/AF03239079/o/151110030233513871809660.jpg
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回答 (2)
2011-10-03 8:47 pm
✔ 最佳答案
11(*)80=1+(1+1)+(1+2)+(1+3)+---+(1+80-1) =1+2+3+---+80=(1+80)*80/2=3240 x(*)10=x+(x+1)+(x+2)+----+(x+10-1)=75 =[(x+10-1)+x]*10/2=75==>x=3
註:新符號暫用(*),因打不出
2011-10-03 8:33 pm
a&b=p(n)=a+a+1+a+2+...+(a+b-1)
=an-b+(1+n)n/2
1&80
=1*80-80-1+(1+80)*80/2
=3240
lhs=75
rhs=a*10-10+(1+10)*10/2
a=3
=an-b+(1+n)n/2
1&80
=1*80-80-1+(1+80)*80/2
=3240
lhs=75
rhs=a*10-10+(1+10)*10/2
a=3
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原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20111003000015KK02335