题目内容
84×[10.8÷(48.6+5.4)-0.2] | [(5
| ||||||||||||||||||||
|
1-3+5-7+9-11+13-…-39+41 | ||||||||||||||||||||
|
| ||||||||||||||||||||
(1-
|
分析:(1)先算小括号内的,再算中括号内的,最后算括号外的;
(2)先算小括号内的,然后算中括号内的,再算括号外的除法,最后算加法;
(3)通过对分母拆分,运用运算定律,变成与分子部分相同的算式,计算即可;
(4)仔细观察,发现1-3=-2,5-7=-2,…,37-39=-2,共分成10组,最后再加上41即可;
(5)通过数字变形,运用乘法分配律简算;
(6)通过数字拆分,约分计算;
(7)1-
=
=
=1×
,1-
=
=
=2×
,…1-
=8×
,所以原式=
,约分计算即可.
(2)先算小括号内的,然后算中括号内的,再算括号外的除法,最后算加法;
(3)通过对分母拆分,运用运算定律,变成与分子部分相同的算式,计算即可;
(4)仔细观察,发现1-3=-2,5-7=-2,…,37-39=-2,共分成10组,最后再加上41即可;
(5)通过数字变形,运用乘法分配律简算;
(6)通过数字拆分,约分计算;
(7)1-
3 |
2×4 |
8-3 |
2×4 |
5 |
2×4 |
5 |
2×4 |
3 |
3×5 |
12 |
3×5 |
2×6 |
3×5 |
6 |
3×5 |
3 |
7×9 |
12 |
9×11 |
(1×2×…×8)×(5×6×…×12) |
(2×3×…×9)×(4×5×…×11) |
解答:解:(1)84×[10.8÷(48.6+5.4)-0.2],
=84×[10.8÷54-0.2],
=84×[0.2-0.2],
=0;
(2)[(5
-4.25)×
]÷
+3.3÷1
,
=[(5.25-4.25)×
]÷
+3.3×
,
=
×
+1.8,
=
+1
,
=3
;
(3)
,
=
,
=
,
=2014;
(4)1-3+5-7+9-11+13-…-39+41,
=(1-3)+(5-7)+(9-11)+…+(37-39)+41,
=41-2-2-2-…-2,
=41-2×10,
=41-20,
=21;
(5)
×
+
×
+
×
,
=
×
+
×
+
×
,
=
×(
+
+
),
=
×
,
=
;
(6)
+
+
+
,
=
+
+
+
,
=
+
+
+
,
=1;
(7)(1-
)×(1-
)×(1-
)×…×(1-
),
=(1×
)×(2×
)×…×(8×
),
=
,
=
,
=
.
=84×[10.8÷54-0.2],
=84×[0.2-0.2],
=0;
(2)[(5
1 |
4 |
5 |
8 |
3 |
8 |
5 |
6 |
=[(5.25-4.25)×
5 |
8 |
3 |
8 |
6 |
11 |
=
5 |
8 |
8 |
3 |
=
5 |
3 |
4 |
5 |
=3
7 |
15 |
(3)
2014×(3.4×69+3.5) |
3.5×69-3.4 |
=
2014×(3.4×69+3.5) |
(3.4+0.1)×69-3.4 |
=
2014×(3.4×69+3.5) |
3.4×69+3.5 |
=2014;
(4)1-3+5-7+9-11+13-…-39+41,
=(1-3)+(5-7)+(9-11)+…+(37-39)+41,
=41-2-2-2-…-2,
=41-2×10,
=41-20,
=21;
(5)
7 |
29 |
3 |
8 |
6 |
29 |
7 |
12 |
3 |
29 |
7 |
9 |
=
7 |
29 |
3 |
8 |
7 |
29 |
1 |
2 |
7 |
29 |
1 |
3 |
=
7 |
29 |
3 |
8 |
1 |
2 |
1 |
3 |
=
7 |
29 |
29 |
24 |
=
7 |
24 |
(6)
1 |
21 |
202 |
2121 |
50505 |
212121 |
13131313 |
21212121 |
=
1 |
21 |
2×101 |
21×101 |
5×10101 |
21×10101 |
13×1010101 |
21×1010101 |
=
1 |
21 |
2 |
21 |
5 |
21 |
13 |
21 |
=1;
(7)(1-
3 |
2×4 |
3 |
3×5 |
3 |
4×6 |
3 |
7×9 |
=(1×
5 |
2×4 |
6 |
3×5 |
12 |
9×11 |
=
(1×2×…×8)×(5×6×…×12) |
(2×3×…×9)×(4×5×…×11) |
=
1×12 |
9×4 |
=
1 |
3 |
点评:完成此题,应仔细观察算式特点,灵活运用运算定律或运算技巧,巧妙灵活地解答.

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(1)张艳(女)10米×4是11″8;1分钟仰卧起坐40次;立定跳远1.92米,她的总得分是
(2)王刚(男)达标抽测以上三项一共得了270分,他10米×4是
(3)男、女生立定跳远成绩排列的规律是