题目内容
计算下列各题
(1)-8-(-17)
(2)(-3)-4-(-9)
(3)[-
×(-
)+(-
)×
]×(-
)
(4)(-0.125)×(-
)×(-8)×7.
(1)-8-(-17)
(2)(-3)-4-(-9)
(3)[-
1 |
3 |
1 |
2 |
1 |
9 |
3 |
2 |
1 |
2 |
(4)(-0.125)×(-
4 |
7 |
分析:(1)把减法改为加法运算;
(2)先化简,再分类计算;
(3)先算括号内的乘法,再算括号内的加法,再算括号外的乘法;
(4)先判定符号,再利用乘法交换律与结合律简算.
(2)先化简,再分类计算;
(3)先算括号内的乘法,再算括号内的加法,再算括号外的乘法;
(4)先判定符号,再利用乘法交换律与结合律简算.
解答:解:(1)-8-(-17)
=-8+17
=9;
(2)(-3)-4-(-9)
=-3-4+9
=2;
(3)[-
×(-
)+(-
)×
]×(-
)
=(
-
)×(-
)
=0;
(4)(-0.125)×(-
)×(-8)×7
=-0.125×8×
×7
=-4.
=-8+17
=9;
(2)(-3)-4-(-9)
=-3-4+9
=2;
(3)[-
1 |
3 |
1 |
2 |
1 |
9 |
3 |
2 |
1 |
2 |
=(
1 |
6 |
1 |
6 |
1 |
2 |
=0;
(4)(-0.125)×(-
4 |
7 |
=-0.125×8×
4 |
7 |
=-4.
点评:此题考查有理数的混合运算,注意运算顺序与计算结果的符号.
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