题目内容
递等式计算.(能简算的要简算.)
(1)1
|
(2)3-(
|
(3)
| ||||||||||||||||||
(4)
|
(5)
|
(6)
|
分析:(1)根据连减的性质进行计算;
(2)先算小括号里面的减法,再算括号外面的减法;
(3)根据加法交换律和结合律进行计算;
(4)先算加法,再算减法;
(5)根据连减的性质进行简算;
(6)先算加法,再算减法.
(2)先算小括号里面的减法,再算括号外面的减法;
(3)根据加法交换律和结合律进行计算;
(4)先算加法,再算减法;
(5)根据连减的性质进行简算;
(6)先算加法,再算减法.
解答:解:
(1)1
-
-
,
=1
-(
+
),
=1
-1,
=
;
(2)3-(
,
=3-
,
=2
;
(3)
+
+
+
,
=(
+
)+(
+
),
=1+1,
=2;
(4)
+
-
,
=
-
,
=
;
(5)
-(
-
),
=
-
+
,
=
+
,
=
;
(6)
+
-
,
=
-
,
=
.
(1)1
| 3 |
| 7 |
| 5 |
| 12 |
| 7 |
| 12 |
=1
| 3 |
| 7 |
| 5 |
| 12 |
| 7 |
| 12 |
=1
| 3 |
| 7 |
=
| 3 |
| 7 |
(2)3-(
| 1 |
| 7 |
=3-
| 1 |
| 56 |
=2
| 55 |
| 56 |
(3)
| 5 |
| 8 |
| 9 |
| 17 |
| 3 |
| 8 |
| 8 |
| 17 |
=(
| 5 |
| 8 |
| 3 |
| 8 |
| 9 |
| 17 |
| 8 |
| 17 |
=1+1,
=2;
(4)
| 5 |
| 9 |
| 2 |
| 3 |
| 15 |
| 18 |
=
| 11 |
| 9 |
| 15 |
| 18 |
=
| 7 |
| 18 |
(5)
| 4 |
| 5 |
| 7 |
| 15 |
| 4 |
| 9 |
=
| 4 |
| 5 |
| 7 |
| 15 |
| 4 |
| 9 |
=
| 1 |
| 3 |
| 4 |
| 9 |
=
| 7 |
| 9 |
(6)
| 7 |
| 8 |
| 1 |
| 6 |
| 11 |
| 24 |
=
| 25 |
| 24 |
| 11 |
| 24 |
=
| 7 |
| 12 |
点评:四则运算,先弄清运算顺序,然后再进一步计算,能简算的要简算.
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