1/2=1/2x1=1-1/2 ,1/6=1/2x3=1/2-1/3,1/12=1/3x4=1/3-1/4.从上面的式子中你发现了什么？用找出的规律计算1/1x2+1/2x3+1/3x4+.....1/49x50观察下面的算是找出类似的规律，3/4+3/4x7+3/7x10+3/10x13 1/3+1/3x5+1/5x7+1/7x9+1/9x11

1x1/2+1/2x1/3+1/3x1/4+.+1/19x1/20=? (-1x1/2)+(-1/2x1/3)+(-1/3x1/4)+...+(-1/2004x1/2005)=? 疑难数学问题火急求助x1^3-3x1^2+2x1+x2→x1（x1^2-2x1+2-x1）+x2→x1（3-x1）+x2 (怎么算出3-X1的)→3x1-x1^2+x2=2x1-x^2+x1+x2=-(x^2-2x1)+x1+x2=-1+2=1 1/2X1/3+1/3X1/4+1/4X1/5+1/5X1/6+.+1/99X1/100=? 1,x1,x2...Xn,成等比数列,x1 x2..xn>0,x1*x2*...xn=?x1,x2...Xn,2成等比数列,x1 x2..xn>0,x1*x2*...xn=? 1x1/2 2x1/3.2007x1/2008怎么做 （-1x1/2）+(-1/2x1/3)+(-1/3x1/4)+.+(-1/99x1/100)=? 1/2x1/3+1/3x1/4+1/4x1/5……+1/99x1/100=? 1x1/2+2x1/3+3x1/4+.+99x1/100 =?有谁知道这道题如何解吗 1/2x1/3+1/3x1/4+.1/8x1/9= 1/2X1/3+1/3X1/4+~+1/8x1/9=? 设0Xn=(Xn-1)*[1-(Xn-1)]*[1-(Xn-1)-(Xn-1)^2]=-----=X1*[1-X1]*[1-X1-X1^2]*[1-X1-X1^2-X1^3]……[1-X1-X1^2-X1^3-X1^4-……X1^n];此式为（1）式。因为0 数学化简看不懂,第2步怎么来的?x2+1/x2-x1-1/x1=(x2-x1)-(x2-x1)/(x1x2)=(x2-x1)(1-1/x1x2) 若实数x1,x2满足x1^2-3x1+1=0,x2^2-3x2+1=0求x2/x1+x1/x2的值 提问:1x1/2+1/2x1/3+1/3x1/4+1/4x1/5+1/5x1/6+1/6x1/7 用简便方法 简便计算题1x1/2+1/2x1/3+1/3x1/4+1/4x1/5+1/5x1/6+1/6x1/7 已知x1,x2是方程2x^2+3x-4=0的两个根试求：x1+x2,x1.x2,1/x1+1/x2,x1^2+x2^2,(x1+1)(x2+1),x1-x2绝对值,的值. 1X1/2是什么意思