2017 số hạng chắc hắn lẻ ra 1 số 

A = 1 - 2 + 3 - 4 + ... + 2016 - 2017

   = ( 1 - 2 ) + ( 3 - 4 ) + .... + ( 2016 - 2017) + 1009

   = (-1) + (-1) + .... + (-1) + 1009 ( Có 1008 cặp nên có 1008 số -1)

  = (-1) x 1008 + 1009

  = ( -1008) + 1009

  = 1

A = -1 +( -1 )+.....+ (-1)

A = -1 x ([2017-1] : 2)

A = -1 x 1008=-1008

nếu đúng thì k cho mình nhé

Lê Thị Thơ sai r có 2017 số cơ mà làm sao chia cặp 2 đc

a) (-21) + |-50| + (-29) – |-2016|

= (-21) + 50 + (-29) – 2016

= [(-21) + (-29) + 50] – 2016 = ( -50 +50 ) – 2016

= 0 – 2016 = - 2016 .

b)  36   :   3 2   +   3 2   .   2 3   - 15 0

= 36 : 9 + 9 . 8 – 1 = 4 + 72 – 1 = 76 – 1 = 75

c)  (   5 103   –   5 102   –   5 101 )   :   (   5 99   .   26   –   5 99 )

=  (   5 103   –   5 102   –   5 101 )   :   5 99   .   ( 26   –   1 )

=  (   5 103   –   5 102   –   5 101 )   :   (   5 99   .   25 )

=  5 101   (   5 2   –   5 1   –   5 0 )   :   (   5 99   .   5 2   )

= (   5 101   .   19   )   :   5 101   = 19

b1:

1,(-24)+6+10+24=-24+6+10+24=6+10=16

2,15+23+(-25)+(-23)=15+23-25-23=15-25=-10

3,-3+(-350)+(-7)+350=-3-350-7+350=-3-7=-10

4,=0

5,=-41

6,=60

7,=-30

8,=0

b2

(35+75)+(345-35-75)=35+75+345-35-75=345

(2002-79+15)-(-79+15)+2002-79+15+79-15+2002

-(515-80+91)-(2003+80-91)=-515+80-91-2003-80+91=-515-2003=-2518

bài 1 nhác ghi thông cảm nha

1,(-24)+6+10+24

= (-24+24)+6+10

=0+6+10

=16

2,15+23+(-25)+(-23)

=(15-25)+(23-23)

=-10+0

=-10

3,-3+(-350)+(-7)+350

=-(3+7)+(-350+350)

=-10+0

=-10

4,-9+(-11)+21+(-1)

=-(9+1)+(-11+21)

=-10+10

=0

5,(-37)+26+15+37

=(-37+37)+(26+15)

=0+31

=31

6,45+75+(-15)+(-45)

=(45-45)+(75-15)

=0+60

=60

7,(-12)+532+(-18)+(-532)

=-(12+18)+(532-532)

=-30+0

=-30

8,-7+(-20)+57+(-30)

=(-7+57)-(20+30)

=50-50

=0

1,(35+75)+(345-35-75)

= 35+75+345-35-75

= (35-35)+(75-75)+345

=0+0+345

=345

2,(2002-79+15)-(-79+15)

=2002-79+15+79-15

=(-79+79)+(15-15)+2002

=0+0+2002

=2002

3,-(515-80+91)-(2003+80-91)

=-515+80-91-2003-80+91

=(80-80)+(-91+91)-(515+2003)

=0+0+2518

=2518

c) Ta có: \(\dfrac{3}{5}+\dfrac{-5}{20}+\dfrac{30}{75}+\dfrac{-7}{4}\)

\(=\dfrac{3}{5}+\dfrac{2}{5}+\dfrac{-1}{4}+\dfrac{-7}{4}\)

\(=1-2=-1\)

Giải:

a)-1/12+4/3=-1/12+16/12=15/12=5/4

b)(-4/14-3/15)-(1/5-20/35-(-1)).7

=-17/35-22/35.7

=-17/35-22/5

=-171/35

c)3/5+-5/20+30/75+-7/4

=3/5+-1/4+2/5+-7/4

=(3/5+2/5)+(-1/4+-7/4)

=1+-2

=-1

d)5/6.-12/14+7/13

=-5/7+7/13

=-16/91

e)2/-9-5/-36-1/4

=-1/12-1/4

=-1/3

f)2/23+-5/12+7/18+21/23+-7/12

=(2/23+21/23)+(-5/12+-7/12)+7/18

=1+-1+7/18

=7/18

xcsxccsz

1: Ta có: \(2155-\left(174+2155\right)+\left(-68+174\right)\)

\(=2155-174-2155-68+174\)

=-68

2) Ta có: \(-25\cdot72+25\cdot21-49\cdot25\)

\(=-25\cdot\left(72-21+49\right)\)

\(=-25\cdot100=-2500\)

a) 15 . (27 + 18 + 6 ) + 15 . ( 23 +12 ) =  15. 51 + 15 . 35 = 765 + 525 = 1290

b) 14 . 35 . 5 + 10 . 25 . 7 + 20 . 70 = 2450 + 1750 + 1400 = 2452450

c) 53 . ( 51 + 4 ) + 53 . ( 49  + 96 ) + 53 = 53 . 55 + 53 . 145 + 53 = 2915 . 7685 = 22401775

d) 46 . ( 27 +75 ) +8 . ( 58 + 25 ) + 8 . ( 58 + 25 ) . 2 = 46 . 102 + 8 . 83 + 8 . 83 =  4692 + 664 + 664 = 6020