1/(√2+1)+1/(√3+√2)+.+1/(√2012+√2011)
=(√2-1)/((√2+1)(√2-1))+(√3-√2)/((√3+√2)(√3-√2))+.+(√2012-√2011)/((√2012+√2011)(√2012-√2011))
=(√2-1)+(√3-√2)+.+(√2012-√2011)
=√2012-1
1/(√2+1)+1/(√3+√2)+.+1/(√2012+√2011)
=(√2-1)/((√2+1)(√2-1))+(√3-√2)/((√3+√2)(√3-√2))+.+(√2012-√2011)/((√2012+√2011)(√2012-√2011))
=(√2-1)+(√3-√2)+.+(√2012-√2011)
=√2012-1