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计算,1/2x4+1/4x6+1/6x8+.+1/48x50=?,1/2+1/6+1/12+1/20+1/30+1/42

来源:学生作业帮 编辑:作业帮 分类:数学作业 时间:2024/05/16 08:42:31
计算,1/2x4+1/4x6+1/6x8+.+1/48x50=?,1/2+1/6+1/12+1/20+1/30+1/42=?
计算,
1/2x4+1/4x6+1/6x8+.+1/48x50
=1/2×(1/2-1/4+1/4-1/6+1/6-1/8+……+1/48-1/50)
=1/2×(1/2-1/50)
=1/2×12/25
=6/25,
1/2+1/6+1/12+1/20+1/30+1/42
=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7
=1-1/7
=6/7