题目内容
计算
(1)(-24)+(-12)
(2)(+2.3)-(+2.7)
(3)-8-12+2
(4)(-3
)+12.5+(-16
)+(-2.5)
(5)-18+(-7.5)-(-31)-12.5
(6)(-5.6)÷(-14+7)+(-3)×2
(7)(
+
-
)×(-36)
(8)
×(-
)-(-
)×(-
)-
×(-1
)
(9)(-6
)×
-8÷|-4+2|
(10)(-2)2÷(-
)+|-
|×(-24).
(1)(-24)+(-12)
(2)(+2.3)-(+2.7)
(3)-8-12+2
(4)(-3
3 |
7 |
4 |
7 |
(5)-18+(-7.5)-(-31)-12.5
(6)(-5.6)÷(-14+7)+(-3)×2
(7)(
1 |
6 |
5 |
9 |
7 |
12 |
(8)
4 |
9 |
9 |
14 |
5 |
9 |
9 |
14 |
9 |
14 |
2 |
9 |
(9)(-6
1 |
2 |
4 |
13 |
(10)(-2)2÷(-
2 |
3 |
1 |
16 |
分析:(1)根据有理数的加法法则计算即可;
(2)根据有理数的减法法则计算即可;
(3)从左到右的顺序依次计算即可;
(4)先算同分母分数,再相加即可求解;
(5)先化简,再计算即可;
(6)先乘乘除后算加减,有括号的先算括号里面的;
(7)(8)直接运用乘法的分配律计算;
(9)先乘乘除后算加减,有绝对值的先算绝对值里面的;
(10)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.
(2)根据有理数的减法法则计算即可;
(3)从左到右的顺序依次计算即可;
(4)先算同分母分数,再相加即可求解;
(5)先化简,再计算即可;
(6)先乘乘除后算加减,有括号的先算括号里面的;
(7)(8)直接运用乘法的分配律计算;
(9)先乘乘除后算加减,有绝对值的先算绝对值里面的;
(10)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.
解答:解:(1)(-24)+(-12)=-36;
(2)(+2.3)-(+2.7)=-0.4;
(3)-8-12+2=-18;
(4)(-3
)+12.5+(-16
)+(-2.5)
=(-3
-16
)+(12.5-2.5)
=-20+10
=-10;
(5)-18+(-7.5)-(-31)-12.5
=-18-7.5+31-12.5
=-38+31
=-7;
(6)(-5.6)÷(-14+7)+(-3)×2
=5.6÷7-6
=0.8-6
=-5.2;
(7)(
+
-
)×(-36)
=-6-20+21
=-26+21
=-5;
(8)
×(-
)-(-
)×(-
)-
×(-1
)
=(
+
-1
)×(-
)
=(-
)×(-
)
=
;
(9)(-6
)×
-8÷|-4+2|
=-2-8÷2
=-2-4
=-6;
(10)(-2)2÷(-
)+|-
|×(-24)
=4÷(-
)+
×(-16)
=-6-1
=-7.
(2)(+2.3)-(+2.7)=-0.4;
(3)-8-12+2=-18;
(4)(-3
3 |
7 |
4 |
7 |
=(-3
3 |
7 |
4 |
7 |
=-20+10
=-10;
(5)-18+(-7.5)-(-31)-12.5
=-18-7.5+31-12.5
=-38+31
=-7;
(6)(-5.6)÷(-14+7)+(-3)×2
=5.6÷7-6
=0.8-6
=-5.2;
(7)(
1 |
6 |
5 |
9 |
7 |
12 |
=-6-20+21
=-26+21
=-5;
(8)
4 |
9 |
9 |
14 |
5 |
9 |
9 |
14 |
9 |
14 |
2 |
9 |
=(
4 |
9 |
5 |
9 |
2 |
9 |
9 |
14 |
=(-
2 |
9 |
9 |
14 |
=
1 |
7 |
(9)(-6
1 |
2 |
4 |
13 |
=-2-8÷2
=-2-4
=-6;
(10)(-2)2÷(-
2 |
3 |
1 |
16 |
=4÷(-
2 |
3 |
1 |
16 |
=-6-1
=-7.
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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