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2/3x4x5+2/4x5x6+2/5x6x7+2/6x7x8+2/7x8x9+2/8x9x10=()
题目详情
2/3x4x5+2/4x5x6+2/5x6x7+2/6x7x8+2/7x8x9+2/8x9x10=( )
▼优质解答
答案和解析
2/3x4x5+2/4x5x6+2/5x6x7+2/6x7x8+2/7x8x9+2/8x9x10=( )
=1/3*4-1/4*5+1/4*5-1/5*6+...+1/8*9-1/9*10
=1/3*4-1/9*10
=1/12-1/90
=13/180
=1/3*4-1/4*5+1/4*5-1/5*6+...+1/8*9-1/9*10
=1/3*4-1/9*10
=1/12-1/90
=13/180
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