2/1X3+2/3X5+2/5x7+.+2/19x21
2/1X3+2/3X5+2/5x7+.+2/19x21
2/1X3+2/3X5+2/5x7+.+2/19x21全过程(最好带原因),
(2X2)/1X3+(4X4)/(3X5)+(6X6)/(5X7)+...+(20X20)/(19X21)==?
1/1X3+1/3X5+1/5X7...1/17X19+1/19X21=
2/1x3+2/3X5+2/5x7=2/7x9+2/9x11
1x2/1+2x3/1+3x4/1+4x5/1+5x6/1+6x7/1
1/1x2+1/2x3+1/3x4+1/4x5+1/5x6+1/6x7
已知1-1/3=2/1x3,计算1/1x3+1/3x5+1/5x7+1/7x9+1/9x11=
1+2X3+4X5+6X7+8X9=303
先阅读再计算2/1x3=1-1/32/3x5=1/3-1/52/5x7=1/5-7=1/7试计算1/1x3+1/3x5+
2/1x3 + 2/3x5 + 2/5x7 +······+ 2/97x99 + 2/99x101 简便计算
用数学归纳法证明1/(1x3)+1/(3x5)+1/(5x7)…1/(2n-1)(2n+1)=n/(2n+1)