2/1X3+2/3X5+2/5X7+...+2/97X99
2/1x3 + 2/3x5 + 2/5x7 +······+ 2/97x99 + 2/99x101 简便计算
2/1x3+2/3X5+2/5x7=2/7x9+2/9x11
2/1X3+2/3X5+2/5x7+.+2/19x21
2/1X3+2/3X5+2/5x7+.+2/19x21全过程(最好带原因),
1x2/1+2x3/1+3x4/1+4x5/1+5x6/1+6x7/1
1/1x2+1/2x3+1/3x4+1/4x5+1/5x6+1/6x7
(2X2)/1X3+(4X4)/(3X5)+(6X6)/(5X7)+...+(20X20)/(19X21)==?
2/1x2+2/2x3+2/3x4+2/4x5+...+2/98x99+2/99x100
1/1x2+1/2x3+1/3x4+1/4x5+.+1/98x99+1/99x100
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
已知1-1/3=2/1x3,计算1/1x3+1/3x5+1/5x7+1/7x9+1/9x11=