2X4/1 + 4X6/1 + 6X8/1 + 8X10/1 + …… + 48X50/1
2X4/1 + 4X6/1 + 6X8/1 + 8X10/1 + …… + 48X50/1
我觉得你想表达的意思和你打的不一样,错了不要怪我. 1/（2*4）可以看成1/2*（1/2-1/4）,把每项都拆开,前后抵消,易得结果为1/2*（1/2-1/50）=12/50
2x4/1+4x6/1+6x8/1+……48x50/1
2x4/1+4x6/1+6x8/1+…+2006x2008/1 =（2/1-4/2+4/1-6/1+6/1-8/1+……+2006/1-2008/1）÷2 =（2/1-2008/1）÷2 =2008/1003÷2 =4016/1003
2x4/1+4x6/1+6x8/1......+96x98/1+98x100/1=
原题=1/2（1/2-1/4+1/4-1/6.......+1/98-1/100）=1/2（1/2-1/100）=49/200
1/2X4+1/4X6+1/6X8+1/8X10+1/10X12=
1/2X4+1/4X6+1/6X8+1/8X10+1/10X12
=(1/2-1/4+1/4-1/6+1/6-1/8+1/8-1/10+1/10-1/12)÷2
=（1/2-1/12）÷2
=5/12÷2
=5/24
1/2x4+1/4x6+1/6x8+……+l/48x50
原式=1/4x(1/1x2+1/2x3+1/3x4+......+1/24x25)
=1/4x(1-1/2+1/2-1/3+1/3-1/4+......+1/24-1/25)
=1/4x(1-1/25)
=6/25
数列1/2x4+1/4x6+1/6x8+1/8x10+.....1/1996x1998等于多少
1/2x4+1/4x6+1/6x8+1/8x10+.....1/1996x1998
=1/4(1/1×2+1/2×3+1/3×4+……+1/998×999)
=1/4(1-1/2+1/2-1/3+1/3-1/4+……+1/998-1/999)
=1/4(1-1/999)
=499/1998
2x3/1+3x4/1+4x5/1+5x6/1+6x7/1+7x8/1+8x9/1+9x10/1+10x11/1=
解：①2x3/1+3x4/1+4x5/1+5x6/1+6x7/1+7x8/1+8x9/1+9x10/1+10x11/1
=6+12+20+30+42+56+72+90+110
=(6+12+72)+(20+30+90+110)+(42+56)
=90+250+98
=438
②如果楼主原意这样，那么解法不同：
1/2x3+1/3x4+1/4x5+1/5x6+1/6x7+1/7x8+1/8x9+1/9x10+1/10x11
=1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+6/1-1/7+1/7-1/8+1/8-1/9+1/9-1/10+1/10-1/11
=1/2-1/11
=9/22
（亲，希望能对你有所帮助，合作愉快，感谢采纳哦！^-^）
【俊狼猎英】团队为您解答
2x4/1+4x6/1+6x8/1+…+2008/2010=？
1/(2x4）表示(2x4)的倒数
解：原式=1/(2x4)+1/(4x6)+1/(6x8)+…+1/(2008x2010)
=(1/2)x(1/2-1/4+1/4-1/6+1/6-1/8+…+1/2008-1/2010
=(1/2)x(1/2-1/2010)
=251/1005
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
1/2×4+1/4x6+1/6x8+.......1/98x100
1/2×4+1/4x6+1/6x8+.......1/98x100
=1/2×（1/2-1/4+1/4-1/6+……+1/98-1/100）
=1/2×（1/2-1/100）
=1/2×49/100
=49/200
