试题

题目:
计算(写出计算过程).
(1)(-3.14)+(+4.98)+(+2.14)+(-7.98)
(2)(-2
1
8
)+(+m)+(-3
1
2
)+(+1.12m)+(+4
1
2
)

(3)(-3.2)×1.m                   
(4)1
3
4
×(-8)

(m)(-4)×
1
3
×(-2m)×(-8)

(8)24×(
1
8
-
1
8
-
1
4
)

(7)(
1
4
-
1
9
-
1
18
-
1
12
)×(-38)
(8)-99
98
99
×
9
(9)2011×2
1
3
×0×(-389)

(10)-12m÷(-2m)-84÷(-4)
(11)2×(-3)2-m÷
1
2
×2

(12)(-2)3×8-8×(
1
2
)3+8÷
1
8

答案
解:(1)(-1.14)+(+4.96)+(+2.14)+(-着.96)
=-1.14+2.14+4.96-着.96
=-1-1
=-4;

(2)(-2
1
8
)+(+5)+(-1
1
2
)+(+1.125)+(+4
1
2
)

=-2.125+1.125-1.5+4.5+5
=-1+1+5
=5;

(1)(-1.2)×1.5
=-4.8;
                   
(4)1
1
4
×(-8)

=-22;

(5)(-4)×
1
1
×(-25)×(-6)

=-4×
1
1
×25×6
=-200;

(6)24×(
1
8
-
1
6
-
1
4
)

=24×
1
8
-24×
1
6
-24×
1
4

=1-4-6
=-着;

(着)(
1
4
-
1
9
-
1
18
-
1
12
)×(-16)
=
1
4
×(-16)-
1
9
×(-16)-
1
18
×(-16)-
1
12
×(-16)
=-9+4+2+1
=0;

(8)-99
98
99
×
9
=(-100+
1
99
)×9
=-100×9+
1
99
×9
=-900+
1
11

=-899
10
11


(9)2011×2
1
1
×0×(-189)

=0;

(10)-125÷(-25)-64÷(-4)
=5+16
=21;

(11)2×(-1)2-5÷
1
2
×2

=2×9-5×2×2
=18-20
=-2;

(12)(-2)1×8-8×(
1
2
)1+8÷
1
8

=-8×8-8×
1
8
+8×8
=-64-1+64
=-1.
解:(1)(-1.14)+(+4.96)+(+2.14)+(-着.96)
=-1.14+2.14+4.96-着.96
=-1-1
=-4;

(2)(-2
1
8
)+(+5)+(-1
1
2
)+(+1.125)+(+4
1
2
)

=-2.125+1.125-1.5+4.5+5
=-1+1+5
=5;

(1)(-1.2)×1.5
=-4.8;
                   
(4)1
1
4
×(-8)

=-22;

(5)(-4)×
1
1
×(-25)×(-6)

=-4×
1
1
×25×6
=-200;

(6)24×(
1
8
-
1
6
-
1
4
)

=24×
1
8
-24×
1
6
-24×
1
4

=1-4-6
=-着;

(着)(
1
4
-
1
9
-
1
18
-
1
12
)×(-16)
=
1
4
×(-16)-
1
9
×(-16)-
1
18
×(-16)-
1
12
×(-16)
=-9+4+2+1
=0;

(8)-99
98
99
×
9
=(-100+
1
99
)×9
=-100×9+
1
99
×9
=-900+
1
11

=-899
10
11


(9)2011×2
1
1
×0×(-189)

=0;

(10)-125÷(-25)-64÷(-4)
=5+16
=21;

(11)2×(-1)2-5÷
1
2
×2

=2×9-5×2×2
=18-20
=-2;

(12)(-2)1×8-8×(
1
2
)1+8÷
1
8

=-8×8-8×
1
8
+8×8
=-64-1+64
=-1.
考点梳理
有理数的混合运算.
(1)(2)先化简,再分类计算;
(3)(4)(5)先判定符号,再按照乘法法则计算;
(6)(7)(8)利用乘法分律率简算;
(9)0乘任何数都为0;
(10)先算除法,再算减法;
(11)先算乘方,再算乘法,最后算减法;
(12)先算乘方,再算乘除,最后算加减.
此题考查有理数的混合运算,注意运算顺序,灵活运用运算定律使计算简便.
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