题目
计算下面各题。
①
-
+
②
+
-
③
-(
+
)
④
-(
-
)
⑤
+
-
⑥
+(
+
+
)
答案:① 5 6 - 1 3 + 1 2 = 5 6 - 2 6 + 3 6 = 3 6 + 3 6 =1 ② 1 2 + 1 4 - 1 6 = 6 12 + 3 12 - 2 12 = 7 12 ③ 9 4 -( 1 4 + 1 5 ) = 9 4 - 1 4 - 1 5 = 8 4 - 1 5 =2- 1 5 =1 4 5 ④ 11 12 -( 1 4 - 1 6 ) = 11 12 -( 3 12 - 2 12 ) = 11 12 - 1 12 = 5 6 ⑤ 1 5 + 5 7 - 4 5 = 7 35 + 25 35 - 28 35 = 4 35 ⑥ 5 8 +( 5 6 + 3 8 + 1 6 ) = 5 8 + 5 6 + 3 8 + 1 6 = 5 8 + 3 8 + 5 6 + 1 6 =1+1 =2