试题

题目:
计算:
(1)0.125×(-7)×8;
(2)-
1
12
十(0.3×3
1
3
+
1
3
)÷|-
1
4
|;
(3)-9
22
23
×(-69);
(4)(-1
1
2
-
3
8
+
7
12
)÷(-
1
24
);
(5)[2
1
2
-(
7
9
-
11
12
+
1
6
)×36]÷5;
(6)(-370)×(-
1
4
)+0.25×24.5+(-5
1
2
)×(-25%).
答案
解:(1)原式=(0.125×8)×(-7)
=1×(-7)
=-7;

(2)原式=-
1
12
+(
3
10
×
10
3
+
1
3
)÷
1
4

=-
1
12
+
4
3
×4
=-
1
12
+
16
3

=
21
4


(3)原式=(-10+
1
23
)×(-69)
=(-10)×(-69)+
1
23
×(-69)
=690-3
=687;

(4)原式=(-1
1
2
)×(-24)-
3
8
×(-24)+
7
12
×(-24)
=36+9-14
=31;

(5)原式=[
5
2
-(
7
9
×36-
11
12
×36+
1
6
×36)]÷5
=[
5
2
-(28-33+6)]÷5
=[
5
2
-1]÷5
=
3
2
×
1
5

=
3
10


(6)原式=370×
1
4
+
1
4
×24.5+
11
2
×
1
4

=
1
4
×(370+24.5+
11
2

=
1
4
×400
=100.
解:(1)原式=(0.125×8)×(-7)
=1×(-7)
=-7;

(2)原式=-
1
12
+(
3
10
×
10
3
+
1
3
)÷
1
4

=-
1
12
+
4
3
×4
=-
1
12
+
16
3

=
21
4


(3)原式=(-10+
1
23
)×(-69)
=(-10)×(-69)+
1
23
×(-69)
=690-3
=687;

(4)原式=(-1
1
2
)×(-24)-
3
8
×(-24)+
7
12
×(-24)
=36+9-14
=31;

(5)原式=[
5
2
-(
7
9
×36-
11
12
×36+
1
6
×36)]÷5
=[
5
2
-(28-33+6)]÷5
=[
5
2
-1]÷5
=
3
2
×
1
5

=
3
10


(6)原式=370×
1
4
+
1
4
×24.5+
11
2
×
1
4

=
1
4
×(370+24.5+
11
2

=
1
4
×400
=100.
考点梳理
有理数的混合运算.
(1)根据乘法交换律进行计算即可;
(2)先算括号里面的,再算除法,最后算加减即可;
(3)根据乘法分配律进行计算即可;
(4)根据乘法分配律进行计算即可;
(5)先算小括号里面的,再算中括号里面的,最后算除法;
(6)根据乘法分配律进行计算即可.
本题考查的是有理数的混合运算,在进行有理数的混合运算时,注意各个运算律的运用,使运算过程得到简化.
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