题目内容
计算
(1)1÷(
-
)×21;
(2)(-12-4)÷(-2);
(3)-2.7×56+7.9×(-56)+6×5.6(用简便方法计算).
(1)1÷(
1 |
7 |
2 |
7 |
(2)(-12-4)÷(-2);
(3)-2.7×56+7.9×(-56)+6×5.6(用简便方法计算).
(1)1÷(
-
)×21
=1÷(-
)×21
=1×(-7)×21
=-147;
(2)(-12-4)÷(-2)
=-16÷(-2)
=8;
(3)-2.7×56+7.9×(-56)+6×5.6
=-2.7×56-7.9×56+0.6×56
=(-2.7-7.9+0.6)×56
=-10×56
=-560.
1 |
7 |
2 |
7 |
=1÷(-
1 |
7 |
=1×(-7)×21
=-147;
(2)(-12-4)÷(-2)
=-16÷(-2)
=8;
(3)-2.7×56+7.9×(-56)+6×5.6
=-2.7×56-7.9×56+0.6×56
=(-2.7-7.9+0.6)×56
=-10×56
=-560.
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