Đáp án:
` (200 - (3 + 2/3 + 2/4 + 2/5 + .......... + 2/100))/( 1/2 + 2/3 + 3/4 + .......... + 99/100)`
` = (200 - 2 - 1 - 2/3 - 2/4 - 2/5 - ........... - 2/100)/( 1 - 1/2 + 1 - 1/3 + 1 - 1/4 + ............ + 1 - 1/100)`
` = (200 - 2 - (1 + 2/3 + 2/4 + ............. + 2/100) )/( (1 + 1 + 1 +........... + 1) - (1/2 + 1/3 + 1/4 + ........... + 1/100) )`
` = (198 - (1 + 2/3 + 2/4 + .......... + 2/100) )/( 99 - (1/2 + 1/3 + 1/4 + ............ + 1/100) )`
` = (2 . (99 - ( 1/2 + 1/3 + 1/4 + ........ + 1/100) ) )/(99 - (1/2 + 1/3 + 1/4 + .......... + 100) )`
` = 2/1 = 2`