题目内容
用递等式计算:(怎样简便就怎样算)
(1)2÷
-
÷2;
(2)4
×0.75+
×7.25;
(3)
-0.75×
;
(4)5-(3
÷0.7×
+
);
(5)3
-(0.2+
)×4.5;
(6)
×[(2.75-1.5)÷
+2
].
(1)2÷
2 |
7 |
2 |
7 |
(2)4
3 |
4 |
3 |
8 |
(3)
2 |
5 |
4 |
15 |
(4)5-(3
1 |
2 |
1 |
7 |
5 |
14 |
(5)3
3 |
4 |
1 |
3 |
(6)
6 |
23 |
5 |
6 |
1 |
3 |
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)先算除法,再算减法;
(2)先算乘法,再算加法;
(3)先算乘法,再算减法;
(4)先算除法,再算乘法,再算加法,最后算减法;
(5)根据乘法分配律进行简算,最后算减法;
(6)先算减法,再算除法,再算加法,最后算乘法.
(2)先算乘法,再算加法;
(3)先算乘法,再算减法;
(4)先算除法,再算乘法,再算加法,最后算减法;
(5)根据乘法分配律进行简算,最后算减法;
(6)先算减法,再算除法,再算加法,最后算乘法.
解答:
解:(1)2÷
-
÷2
=7-
=6
;
(2)4
×0.75+
×7.25
=3.5625+2.71875
=6.28125;
(3)
-0.75×
=
-
=
;
(4)5-(3
÷0.7×
+
)
=5-(5×
+
)
=5-(
+
)
=5-1
=3
;
(5)3
-(0.2+
)×4.5
=3
-(0.2×4.5+
×4.5)
=3
-(0.9+1.5)
=3
-2.4
=1.35;
(6)
×[(2.75-1.5)÷
+2
]
=
×[1.25÷
+2
]
=
×[1.5+2
]
=
×3
=1.
2 |
7 |
2 |
7 |
=7-
1 |
7 |
=6
6 |
7 |
(2)4
3 |
4 |
3 |
8 |
=3.5625+2.71875
=6.28125;
(3)
2 |
5 |
4 |
15 |
=
2 |
5 |
1 |
5 |
=
1 |
5 |
(4)5-(3
1 |
2 |
1 |
7 |
5 |
14 |
=5-(5×
1 |
7 |
5 |
14 |
=5-(
5 |
7 |
5 |
14 |
=5-1
1 |
14 |
=3
13 |
14 |
(5)3
3 |
4 |
1 |
3 |
=3
3 |
4 |
1 |
3 |
=3
3 |
4 |
=3
3 |
4 |
=1.35;
(6)
6 |
23 |
5 |
6 |
1 |
3 |
=
6 |
23 |
5 |
6 |
1 |
3 |
=
6 |
23 |
1 |
3 |
=
6 |
23 |
5 |
6 |
=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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