题目内容
简便计算:
(1)-
×(10-1
+0.5);
(2)(-11
)÷
-21
×(-
)-19
×
.
(1)-
4 |
5 |
1 |
4 |
(2)(-11
2 |
3 |
5 |
6 |
1 |
2 |
6 |
5 |
1 |
3 |
6 |
5 |
分析:(1)把带分数化为假分数,然后利用乘法分配律进行计算即可得解;
(2)把除法转化为乘法,然后逆运用乘法分配律进行计算即可得解.
(2)把除法转化为乘法,然后逆运用乘法分配律进行计算即可得解.
解答:解:(1)-
×(10-1
+0.5),
=10×(-
)-
×(-
)+
×(-
),
=-8+1-
,
=-7
;
(2)(-11
)÷
-21
×(-
)-19
×
,
=(-11
)×
÷
+21
×
-19
×
,
=(-11
+21
-19
)×
,
=(-10+
)×
,
=-10×
+
×
,
=-12+
,
=-11
.
4 |
5 |
1 |
4 |
=10×(-
4 |
5 |
5 |
4 |
4 |
5 |
1 |
2 |
4 |
5 |
=-8+1-
2 |
5 |
=-7
2 |
5 |
(2)(-11
2 |
3 |
5 |
6 |
1 |
2 |
6 |
5 |
1 |
3 |
6 |
5 |
=(-11
2 |
3 |
6 |
5 |
5 |
6 |
1 |
2 |
6 |
5 |
1 |
3 |
6 |
5 |
=(-11
2 |
3 |
1 |
2 |
1 |
3 |
6 |
5 |
=(-10+
1 |
2 |
6 |
5 |
=-10×
6 |
5 |
1 |
2 |
6 |
5 |
=-12+
3 |
5 |
=-11
2 |
5 |
点评:本题考查了有理数的乘法,利用运算定律可以使计算更加简便.

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