题目内容
计算:
(1)-23÷
×(-
)2
(2)[1-(1-0.5×
)]×[2-(-3)2].
(3)-|-3+2
|-|-
|2+(-
)2×(-1)9×(-2)3
(4)-22×(-3.14)-3.14×(-
)×(-6);
(5)(
-
-
)÷(-
)+(-
).
(1)-23÷
| 4 |
| 9 |
| 2 |
| 3 |
(2)[1-(1-0.5×
| 1 |
| 3 |
(3)-|-3+2
| 1 |
| 3 |
| 1 |
| 3 |
| 1 |
| 3 |
(4)-22×(-3.14)-3.14×(-
| 1 |
| 2 |
(5)(
| 7 |
| 4 |
| 7 |
| 8 |
| 7 |
| 12 |
| 7 |
| 8 |
| 8 |
| 3 |
分析:(1)(2)(3)(4)按照有理数混合运算的顺序,先乘方后乘除最后算加减,有括号的先算括号里面的;
(5)运用乘法的分配律计算.
(5)运用乘法的分配律计算.
解答:解:(1)-23÷
×(-
)2
=-8×
×
=-8;
(2)[1-(1-0.5×
)]×[2-(-3)2]
=[1-(1-
)]×[2-9]
=[1-
]×[-7]
=
×[-7]
=-
;
(3)-|-3+2
|-|-
|2+(-
)2×(-1)9×(-2)3
=-
-
+
×(-1)×(-8)
=-
-
+
=
;
(4)-22×(-3.14)-3.14×(-
)×(-6)
=-4×(-3.14)-3.14×3
=(4-3)×3.14
=1×3.14
=3.14;
(5)(
-
-
)÷(-
)+(-
)
=(
-
-
)×(-
)+(-
)
=(-
×
+
×
+
×
)+(-
)
=-2+1+
-
)
=-3.
| 4 |
| 9 |
| 2 |
| 3 |
=-8×
| 9 |
| 4 |
| 4 |
| 9 |
=-8;
(2)[1-(1-0.5×
| 1 |
| 3 |
=[1-(1-
| 1 |
| 6 |
=[1-
| 5 |
| 6 |
=
| 1 |
| 6 |
=-
| 7 |
| 6 |
(3)-|-3+2
| 1 |
| 3 |
| 1 |
| 3 |
| 1 |
| 3 |
=-
| 2 |
| 3 |
| 1 |
| 9 |
| 1 |
| 9 |
=-
| 2 |
| 3 |
| 1 |
| 9 |
| 8 |
| 9 |
=
| 1 |
| 9 |
(4)-22×(-3.14)-3.14×(-
| 1 |
| 2 |
=-4×(-3.14)-3.14×3
=(4-3)×3.14
=1×3.14
=3.14;
(5)(
| 7 |
| 4 |
| 7 |
| 8 |
| 7 |
| 12 |
| 7 |
| 8 |
| 8 |
| 3 |
=(
| 7 |
| 4 |
| 7 |
| 8 |
| 7 |
| 12 |
| 8 |
| 7 |
| 8 |
| 3 |
=(-
| 7 |
| 4 |
| 8 |
| 7 |
| 7 |
| 8 |
| 8 |
| 7 |
| 7 |
| 12 |
| 8 |
| 7 |
| 8 |
| 3 |
=-2+1+
| 2 |
| 3 |
| 8 |
| 3 |
=-3.
点评:本题考查的是有理数的运算能力.注意:
(1)要正确掌握运算顺序,在混合运算中要特别注意运算顺序:先三级,后二级,再一级;有括号的先算括号里面的;同级运算按从左到右的顺序;
(2)去括号法则:--得+,-+得-,++得+,+-得-.
(1)要正确掌握运算顺序,在混合运算中要特别注意运算顺序:先三级,后二级,再一级;有括号的先算括号里面的;同级运算按从左到右的顺序;
(2)去括号法则:--得+,-+得-,++得+,+-得-.
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