1/(2x2-1)+1/(4x4-1)+1/(6x6-1)+-----+1/(100x100-1)=
1X2+2X4+3X6+.50X100
1x1-2x2+3x3-4x4+5x5-6x6.-100x100+101x101
1x2+2x4+3x6+4x8 ------------------------------- 2x3+4x6+6x9+
1x2+2x4+3x6+.+1005x2010
(1x2+2x4+3x6+4x8)/(2x3+4x6+6x9+8x12)
计算1x2+2x3+3x4+4x5+...+99x100
1x2/1+2x3/1+3x4/1+.+2009x2010/1=? 2x4/1+4x6/1+6x8/1+.+2010x2
x8+x7+x6+x5+x4+x3+x2+x+1因式分解
一定要帮我啊!(1/1x2)+(1/2x3)+(1/3x4)+(1/4x5)+.+(1/99x100)=?
1分之1x2+1分之2x3+1分之3x4.+1分之99x100
(2X2)/1X3+(4X4)/(3X5)+(6X6)/(5X7)+...+(20X20)/(19X21)==?
1x2+2x4+3x6+4x8+5x10+.+20x40 怎么算?