100X100—99X99+98X98+...+2X2—1X1
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100X100—99X99+98X98+...+2X2—1X1100X100—99X99+98X98+...+2X2—1X1100X100—99X99+98X98+...+2X2—1X1100×100
100X100—99X99+98X98+...+2X2—1X1
100X100—99X99+98X98+...+2X2—1X1
100X100—99X99+98X98+...+2X2—1X1
100×100-99×99+98×98+...+2×2－1×1
=(100+99)(100-99)+(98+97)(98-97)+...+(2+1)(2-1)
=(100+99)+(98+97)+...+(2+1)
=5050
我知道1+.....100是多少，就是首相+尾相（即1与100）×项数(即100）÷2就是5050，估计还没到你那种算式的程度，到时候我问问我们奥数老师，看看她知不知道。
100X100—99X99+98X98+...+2X2—1X1
100X100—99X99+98X98+...+2X2—1X1等于多少
100X100一99X99+98X98一97X97+,十2X2一1X1
100X100-99X99-98X98-97X97+…+2X2-1X1=?
计算100X100-99X99+98X98-97X97+...+2X2-1X1=
1X1+2X2+3X3+4X4+5X5.+98X98+99X99+100X100=?
100x100-99x99+98x98-97x97+.+4x4-x4-3x3+2x2-1计算
0.25x0.25x...x0.25x4x...x4=1x2分之1+2x3分之1+3x4分之1+4x5分之1+...+97x98分之1+98x99分之1+99x100分之1=(1+2分之1）x（1+3分之1）x（1+4分之1）x...(1+18分之1）x（1+19分之1）x（1+20分之1）=
2x4/1+4x6/1+6x8/1.+96x98/1+98x100/1=
1/1X2+1/2x3+1/3x4+1/4x5+.+1/98x99+1/99x100求结果!
求1x2,2x3,3x4,4x5,……98x99,99x100的倒数和如题
1/1x2+1/2x3+1/3x4+……+1/98x99+1/99x100=……
2/1x2+2/2x3+2/3x4+2/4x5+...+2/98x99+2/99x100
1x2+2x3+3x4+4x5+······98x99+99x100=?
1/1x2+1/2x3+1/3x4+.1/98x99+1/99x100=?要注明运算过程
1/1x2+1/2x3+1/3x4.1/98x99+1/99x100怎么解
1x2/1+2x3/1+3x4/1+……+98x99/1+99x100/1=?
1x1-2x2+3x3-4x4******+99x99-100x100+101x101的过程教教我