1x1=?

1x1+1x1=多少? 1x1=什么 1X1=?为什么? 1x1=多少 1x1=? 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 数学题1/4x1/5x1/6+1/5x1/6x1/7+1/6x1/7x1/8+.+1/98×1/99×1/100=? 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=? 41.8x8.1+11x1.25+53.7x1.9=? 1+1+1x1=? 1+1-1x1=? 成语1X1=1 已知A={x1-1 数学式子变形（x1+1/x1)-(x2+1/x2)=(x1-x2)+(1/x1-1/x2) 如何变形的 （-1x1/2）+(-1/2x1/3)+(-1/3x1/4)+.+(-1/99x1/100)=? 1/2x1/3+1/3x1/4+1/4x1/5……+1/99x1/100=?