试题

题目:
计算:
(1)(+2)+(-11)-6;                          
(2)(-6)×(+8)÷(-12);
(3)-3
3
4
÷5×
1
5
;                         
(4)2×(-3)2-4×(-2)+10;
(5)-9÷3+(
1
2
-
2
3
)×12+32;               
(6)-14-(2.5-2)×
1
4
×[4-(-1)3];
(7)(-0.25)÷(-
2
3
)×(-
5
8
);                   
(8)(-30)×(
1
3
-
5
6
-
3
10
).
答案
解:(1)(+2)+(-11)-6
=2-11-6
=-15;
                          
(2)(-6)×(+8)÷(-12)
=48÷12
=4;

(3)-3
3
4
÷5×
1
5
 
=-
15
4
×
1
5
×
1
5
 
=-
3
20

                        
(4)2×(-3)2-4×(-2)+10
=2×9+8+10
=18+8+10
=36;

(5)-9÷3+(
1
2
-
2
3
)×12+32               
=-3-
1
6
×12+9             
=-3-2+9
=4;

(6)-14-(2.5-2)×
1
4
×[4-(-1)3]
=-1-
1
2
×
1
4
×[4+1]
=-1-
1
2
×
1
4
×5
=-1-
5
8

=-1
5
8


(7)(-0.25)÷(-
2
3
)×(-
5
8

=-
1
4
×
3
2
×
5
8

=-
15
64

                   
(8)(-30)×(
1
3
-
5
6
-
3
10

=-30×
1
3
+30×
5
6
+30×
3
10

=-10+25+9
=24.
解:(1)(+2)+(-11)-6
=2-11-6
=-15;
                          
(2)(-6)×(+8)÷(-12)
=48÷12
=4;

(3)-3
3
4
÷5×
1
5
 
=-
15
4
×
1
5
×
1
5
 
=-
3
20

                        
(4)2×(-3)2-4×(-2)+10
=2×9+8+10
=18+8+10
=36;

(5)-9÷3+(
1
2
-
2
3
)×12+32               
=-3-
1
6
×12+9             
=-3-2+9
=4;

(6)-14-(2.5-2)×
1
4
×[4-(-1)3]
=-1-
1
2
×
1
4
×[4+1]
=-1-
1
2
×
1
4
×5
=-1-
5
8

=-1
5
8


(7)(-0.25)÷(-
2
3
)×(-
5
8

=-
1
4
×
3
2
×
5
8

=-
15
64

                   
(8)(-30)×(
1
3
-
5
6
-
3
10

=-30×
1
3
+30×
5
6
+30×
3
10

=-10+25+9
=24.
考点梳理
有理数的混合运算.
(1)先化简,再计算即可;
(2)从左往右依次计算即可;
(3)(7)将除法变为乘法,再约分计算;
(4)(5)(6)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;
(8)直接运用乘法的分配律计算.
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-.
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