第1个回答 2012-06-25
(1) 2/3 +4/5 -3/10 = 2/3 +8/10 -3/10 =2/3 + 5/10 =2/3 +1/2 =7/6
(2) 11/8 - (5/6 + 3/8)= 11/8 - 5/6 -3/8 =1 -5/6 =1/6
(3)6/7 - (11/14 - 1/2)= 6/7 - 11/14 +1/2 = 1/14 + 1/2 =8/14=4/7
(4)5/9 +4/11 +6/11 +4/9 = 5/9 +4/9 + 4/11 +6/11 = 1+ 10/11 = 21/11