|1∕2009-1∕2010|+|1∕2010﹣1∕2011|﹢|1∕2011-1∕2012|=

问题描述:

|1∕2009-1∕2010|+|1∕2010﹣1∕2011|﹢|1∕2011-1∕2012|=

|1∕2009-1∕2010|+|1∕2010﹣1∕2011|﹢|1∕2011-1∕2012|
=1/2009-1/2010+1/2010-1/2011+1/2011-1/2012
=1/2009-1/2012
=(2012-2009)/(2009x2012)
=3/4042108