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42X（1/8+1/24+1/48+1/120+1/168）求解1/48+1/120中间没有个1/80
题目详情
42X（1/8+1/24+1/48+1/120+1/168）求解
1/48+1/120中间没有个1/80
1/48+1/120中间没有个1/80
▼优质解答
答案和解析
42X（1/8+1/24+1/48+1/80+1/120+1/168
=42*1/8*（1+1/3+1/6+1/10+1/15+1/21)
=42*1/8*(1+1/3+1/6+1/6+1/21)
=1/8*(42+14+7+7+2)
=1/8*72
=9
=42*1/8*（1+1/3+1/6+1/10+1/15+1/21)
=42*1/8*(1+1/3+1/6+1/6+1/21)
=1/8*(42+14+7+7+2)
=1/8*72
=9
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