1/x(x+1)+1/(x+1)(x+2)+……+1/(x+9)(x+10)=1/x+101/x-1/(x+1)+1/(x+1)-1/(x+2)+...+1/(x+9)-1/(x+10)=1/x+101/x-1/(x+10)=1/x+10-1/(x+10)=10x+10=-1/10x=-10.1