原式=1/x-1/(x+1)+1/(x+1)-1/(x+2)+---+1/(x+2010)-1/(x+2011)=1/x-1/(x+2011)=1-1/2012
=2011/2012;
原式=1-1/2+1/2-1/3+1/3-1/4+---+1/99-1/100=1-1/100=99/100;
(4x-5)/(2x^2+x-6)=m/(x+2)+n/(2x-3)
因为等式左边=(4x-5)/(2x-3)(x+2),等式右边=[m(2x-3)+n(x+2)]/(2x-3)(x+2)
所以:4x-5=2mx-3m+nx+2n=x(2m+n)+(2n-3m)
则:1式:2m+n=4,2式:2n-3m=-5
最后解得m=13/7,n=2/7;