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1x1/4+4x1/7+7x1/10+.+97x1/100=
题目详情
1x1/4+4x1/7+7x1/10+.+97x1/100=
▼优质解答
答案和解析
=1/6*(1/1*4-1*4/7)+1/6*(1/4*7-1/7*10)+……+1/6*(1/94*97-1/97*100)
=1/6*(1/1*4-1*4/7+1/4*7-1/7*10+……+1/94*97-1/97*100)
=1/6*(1/1*4-1/97*100)
=101/2425
=1/6*(1/1*4-1*4/7+1/4*7-1/7*10+……+1/94*97-1/97*100)
=1/6*(1/1*4-1/97*100)
=101/2425
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