题目内容
用递等式计算(能简便计算的要写出简算过程). 8
| 11
| ||||||||||||||||||
0.75×10
| (2
| ||||||||||||||||||
4
| 2.1×[2
|
考点:整数、分数、小数、百分数四则混合运算,运算定律与简便运算
专题:运算顺序及法则,运算定律及简算
分析:(1)先算乘除法,再算加减法;
(2)根据减法的性质计算;
(3)将除法变为乘法,再根据乘法分配律计算;
(4)先算小括号里面的加减法,再将括号外面的除法变为乘法,再约分计算即可求解;
(5)先算小括号里面的减法,再算中括号里面的乘法和加法,最后计算括号外面的除法;
(6)先算小括号里面的减法,再算中括号里面的除法和减法,最后计算括号外面的乘法.
(2)根据减法的性质计算;
(3)将除法变为乘法,再根据乘法分配律计算;
(4)先算小括号里面的加减法,再将括号外面的除法变为乘法,再约分计算即可求解;
(5)先算小括号里面的减法,再算中括号里面的乘法和加法,最后计算括号外面的除法;
(6)先算小括号里面的减法,再算中括号里面的除法和减法,最后计算括号外面的乘法.
解答:
解:(1)8
-1
×2
+4
÷
=8
-4+6
=4
+6
=10
;
(2)11
-1
-3
-4
=11
-(1
+3
+4
)
=11
-9
=2
;
(3)0.75×10
+
÷1
+75%
=0.75×10
+0.75×
+0.75
=0.75×(10
+
+1)
=0.75×12
=9;
(4)(2
-1
)÷(
+
)×
=
×
×
=
;
(5)4
÷[7.8+0.625×(2
-1.15)]
=4
÷[7.8+0.625×1.6];
=4
÷[7.8+1]
=
÷
=
;
(6)2.1×[2
-(8
-7.5)÷
]
=2.1×[2
-1÷
]
=2.1×[2
-1
]
=2.1×
=1.
2 |
5 |
2 |
3 |
2 |
5 |
1 |
2 |
3 |
4 |
=8
2 |
5 |
=4
2 |
5 |
=10
2 |
5 |
(2)11
3 |
5 |
2 |
11 |
5 |
11 |
4 |
11 |
=11
3 |
5 |
2 |
11 |
5 |
11 |
4 |
11 |
=11
3 |
5 |
=2
3 |
5 |
(3)0.75×10
2 |
9 |
3 |
4 |
2 |
7 |
=0.75×10
2 |
9 |
7 |
9 |
=0.75×(10
2 |
9 |
7 |
9 |
=0.75×12
=9;
(4)(2
4 |
7 |
11 |
14 |
1 |
4 |
2 |
3 |
7 |
36 |
=
11 |
14 |
12 |
11 |
7 |
36 |
=
1 |
6 |
(5)4
2 |
5 |
3 |
4 |
=4
2 |
5 |
=4
2 |
5 |
=
22 |
5 |
44 |
5 |
=
1 |
2 |
(6)2.1×[2
1 |
3 |
1 |
2 |
7 |
13 |
=2.1×[2
1 |
3 |
7 |
13 |
=2.1×[2
1 |
3 |
6 |
7 |
=2.1×
10 |
21 |
=1.
点评:考查了运算定律与简便运算,四则混合运算.注意运算顺序和运算法则,灵活运用所学的运算定律简便计算.
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