问题 解答题
(1)-7+(+2)
(2)0-(-5)
(3)(-49)-(+91)-(-5)+(-9)
(4)-7+13-6+20
(5)(-1
1
2
)-1
1
4
+(-2
1
2
)-(-3
3
4
)-(-1
1
4

(6)(-5)×(-4
1
5

(7)
3
7
÷(-2
1
7

(8)(-5)×(-7)×2×(-6)
(9)(-
7
8
)×15×(-1
1
7

(10)19
15
17
×(-10)
(11)(-0.125)×0.5×(-100)×8
(12)3×(-2
1
3
)+2×(-2
1
3
)-5×(-
7
3

(13)-22×(-
1
2
)+8÷(-2)2
答案

(1)-7+(+2)=-5;

(2)0-(-5)=5;

(3)(-49)-(+91)-(-5)+(-9)

=-49-91+5-9

=-149+5

=-144;

(4)-7+13-6+20

=-13+33

=20;

(5)(-1

1
2
)-1
1
4
+(-2
1
2
)-(-3
3
4
)-(-1
1
4

=(-1

1
2
-2
1
2
)+(-1
1
4
+1
1
4
+3
3
4

=-4+3

3
4

=-

1
4

(6)(-5)×(-4

1
5
)=21;

(7)

3
7
÷(-2
1
7
)=-
1
5

(8)(-5)×(-7)×2×(-6)

=(-5×2)×[(-7)×(-6)]

=-10×42

=-420;

(9)(-

7
8
)×15×(-1
1
7

=[(-

7
8
)×(-1
1
7
)]×15

=1×15

=15;

(10)19

15
17
×(-10)

=(20-

2
17
)×(-10)

=-200+1

3
17

=-188

14
17

(11)(-0.125)×0.5×(-100)×8

=(-0.125×8)×[0.5×(-100)]

=-1×(-50)

=50

(12)3×(-2

1
3
)+2×(-2
1
3
)-5×(-
7
3

=(3+2-5)×(-

7
3

=0×(-

7
3

=0;

(13)-22×(-

1
2
)+8÷(-2)2

=-4×(-

1
2
)+8÷4

=2+2

=4.

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