试题

题目:
计算:
(1)-72+72÷36                           
(2)3
2
3
×(
1
3
-
1
2
3
11
÷
5
4

(3)(-1)3-(1-
1
2
)÷3×[2-(-3)2]
(4)-92+2×(-3)2-(-6)÷(-
4
3
)

(5)-2×(-
1
2
)2+|-(-2)|3-(-
1
2
)

(6)(
1
50
-1)×(
1
49
-1)×(
1
48
-1)×…×(
1
4
-1)×(
1
3
-1)×(
1
2
-1)

答案
解:(1)-72+72÷36 
=-72+2
=-70;
                          
(2)3
2
3
×(
1
3
-
1
2
3
11
÷
5
4

=
11
3
×(-
1
6
)×
3
11
×
4
5

=
2
15


(3)(-1)3-(1-
1
2
)÷3×[2-(-3)2]
=-1-
1
2
×
1
3
×[2-9]
=-1-
1
6
×[-7]
=-1+
7
6

=
1
6


(4)-92+2×(-3)2-(-6)÷(-
4
3
)

=-81+2×9-4.5
=-81+18-4.5
=-67.5;

(5)-2×(-
1
2
)2+|-(-2)|3-(-
1
2
)

=-2×
1
4
+8+
1
2

=-
1
2
+8+
1
2

=8;

(6)(
1
50
-1)×(
1
49
-1)×(
1
48
-1)×…×(
1
4
-1)×(
1
3
-1)×(
1
2
-1)

=-
49
50
×
48
49
×…×
2
3
×
1
2

=-
1
50

解:(1)-72+72÷36 
=-72+2
=-70;
                          
(2)3
2
3
×(
1
3
-
1
2
3
11
÷
5
4

=
11
3
×(-
1
6
)×
3
11
×
4
5

=
2
15


(3)(-1)3-(1-
1
2
)÷3×[2-(-3)2]
=-1-
1
2
×
1
3
×[2-9]
=-1-
1
6
×[-7]
=-1+
7
6

=
1
6


(4)-92+2×(-3)2-(-6)÷(-
4
3
)

=-81+2×9-4.5
=-81+18-4.5
=-67.5;

(5)-2×(-
1
2
)2+|-(-2)|3-(-
1
2
)

=-2×
1
4
+8+
1
2

=-
1
2
+8+
1
2

=8;

(6)(
1
50
-1)×(
1
49
-1)×(
1
48
-1)×…×(
1
4
-1)×(
1
3
-1)×(
1
2
-1)

=-
49
50
×
48
49
×…×
2
3
×
1
2

=-
1
50
考点梳理
有理数的混合运算.
(1)先算除法,再算加法;
(2)先算括号里面的,再算乘除;
(3)(4)(5))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;
(6)先算括号里面的,再约分化简即可.
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-.
(3)整式中如果有多重括号应按照先去小括号,再去中括号,最后大括号的顺序进行.
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