x(x-1)分之一+x(x+1)分之一+········+(x+9)(x+10)分之一=12分之11 怎么算?

问题描述:

x(x-1)分之一+x(x+1)分之一+········+(x+9)(x+10)分之一=12分之11 怎么算?

x(x-1)分之一+x(x+1)分之一+········+(x+9)(x+10)分之一=1/(x-1)-1/x+1/x-1/(x+1)+.1/(x+9)-1/(x+10)=1/(x-1)-1/(x+10)=11/1212(x+10-x+1)=11(x-1)(x+10)12*11=11(x-1)(x+10)12=(x-1)(x+10)x^2+9x-22=0(x+11...