题目内容
用递等式计算(怎样简便怎样算).
+
+
-
+
+0.6-
-(
-
).
| 1 |
| 5 |
| 3 |
| 8 |
| 4 |
| 5 |
| 8 |
| 9 |
| 2 |
| 3 |
| 1 |
| 3 |
| 17 |
| 19 |
| 17 |
| 19 |
| 5 |
| 8 |
| 5 |
| 8 |
| 1 |
| 2 |
分析:(1)根据加法交换率,先算同分母分数,再计算即可求解;
(2)根据加法结合律,先算同分母分数,再计算即可求解;
(3)根据加法交换率,先算同分母分数,再计算即可求解;
(4)先去括号,算同分母分数,再计算即可求解.
(2)根据加法结合律,先算同分母分数,再计算即可求解;
(3)根据加法交换率,先算同分母分数,再计算即可求解;
(4)先去括号,算同分母分数,再计算即可求解.
解答:解:(1)
+
+
,
=
+
+
,
=1+
,
=1
;
(2)
-
+
,
=
-(
-
),
=
-
,
=
;
(3)
+0.6-
,
=
-
+0.6,
=0+0.6,
=0.6;
(4)
-(
-
)
=
-
+
,
=0+
,
=
.
| 1 |
| 5 |
| 3 |
| 8 |
| 4 |
| 5 |
=
| 1 |
| 5 |
| 4 |
| 5 |
| 3 |
| 8 |
=1+
| 3 |
| 8 |
=1
| 3 |
| 8 |
(2)
| 8 |
| 9 |
| 2 |
| 3 |
| 1 |
| 3 |
=
| 8 |
| 9 |
| 2 |
| 3 |
| 1 |
| 3 |
=
| 8 |
| 9 |
| 1 |
| 3 |
=
| 5 |
| 9 |
(3)
| 17 |
| 19 |
| 17 |
| 19 |
=
| 17 |
| 19 |
| 17 |
| 19 |
=0+0.6,
=0.6;
(4)
| 5 |
| 8 |
| 5 |
| 8 |
| 1 |
| 2 |
=
| 5 |
| 8 |
| 5 |
| 8 |
| 1 |
| 2 |
=0+
| 1 |
| 2 |
=
| 1 |
| 2 |
点评:考查了分数的四则混合运算,关键是灵活运用运算律简便计算.
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