a, -(269-357)+(269-357).

=-269+357+269-357.

=0.

b,(123+345)+(456-123)-[2017-(-345)].

=123+345+456-123-2017-345.

=-1561.

a) - ( 269 - 357 ) + ( 269 - 357 ) 

 = - 269 + 357 + 269 - 357 

 = [( - 269  ) + 269 ] + [(-357) + 357 ]

 = 0 + 0

 = 0

b) ( 123 + 345 ) + ( 456 - 123 ) - [ 2017 - ( -345 ) ]

  = 123 + 345 + 456 - 123 - [ 2017 + 345 ]

  = 123 + 345 + 456 - 123 -  2017 - 345 

   = ( 123 - 123 ) +  ( 345 - 345 ) + 456 - 2017

   = 0 + 0 + ( - 1561 )

   = ( - 1561 )

@ Học tốt @

Nhớ k cho mình nha !!!!! Thank

a) (39 - 2689) + 2689

= 39 + (2689 - 2689)

= 39 + 0

= 39

__

b) - (12 345 - 999) = - (12 345 - 1000+1)

- 12 345 + 12345 + 999 -1000+ 1 = 0

0=0

----

c) (-1312) - (1998 - 1312) 

= (1312 - 1312) - 1998

= 0 - 1998 = -1998

d) (-6955) - 33 - 45 -  (-133)

= -(6955+45) - (33 - 133) 

= -7000 - (-100)

= -7000 + 100 = -6900

e) (-21) - 23 - [16 - (-18) - 18 - 16] + 2144

= -21 - 23 - 16 - 18 + 18 + 16 + 2144

= (16 - 16) + (18 - 18) + (2144 - 21 - 23)

= 0 + 0 + 2100

= 2100

g) (-2020) - 2018 - 2016 - ...-2008

= - [(2020+ 2008): 2 x 7]

= -[(4028): 2 x 7]

= -[2014 x 7]

= - 14098

\(a)\left(3567-214\right)-3557\)

\(=3567-214-3567\)

\(=\left(3567-3567\right)-214\)

\(=0-214=-214\)

\(b)\left(-2017\right)-\left(28-2017\right)\)

\(=\left(-2017\right)-28+2017\)

\(=\left[\left(-2017\right)+2017\right]-28\)

\(=0-28=-28\)

\(c)-\left(269-357\right)+\left(269-357\right)\)

\(=\left(-269\right)+357+269-357\)

\(=\left[\left(-269\right)+269\right]+\left(357-357\right)\)

\(=0+0=0\)

\(d)\left(123+345\right)+\left(456-123\right)+\left[2017-\left(345\right)\right]\)

\(=123+345+456-123+2017-345\)

\(=\left(123-123\right)+\left(345-345\right)+456+2017\)

\(=0+0+456+2017\)

\(=2473\)

#Mạt Mạt#

Bài 2. Tính nhanh
a) 27 + (-2019) + (-27)

= 27 -2019 -27

=(27 - 27) -2019

=0-2019

= -2019

d) (-102) – (345 – 102)

= -102 - 345 +102

= (102 - 102) -345

= 0-345

= -345

b) (-10) + 23 + (-20) + 30

= -10 +23-20+30

= -(10+20) +23 +30

= -30 +23 +30

= (30-30) +23

= 0 +23

= 23

e) (12 + 34 – 56) – (12 – 56)

= 12 +34 -56 -12 +56

= (12-12) + (56-56) +34

= 0+0 +34

= 34

c) (-2).125.(-5).(-8).(+17)

=[(-2) . (-5)] . [ 125.(-8)] . (+17)

= 10 . (-1000).(+17)

= - 10000 . 17

= - 170000

f) 37.(-345) – 345.(-47)

= -345 . (37-47)

= -345.(-10)

=3450

a: \(\left(-10\right)\cdot35+10\cdot\left(-12\right)-\left(-10\right)\)

\(=\left(-10\right)\cdot35+\left(-10\right)\cdot12-\left(-10\right)\)

\(=-10\left(35+12-1\right)=-10\cdot46=-460\)

b: \(20\cdot\left(-345\right)+\left(-20\right)\cdot\left(-315\right)\)

\(=20\cdot\left(-345\right)+20\cdot315\)

\(=20\left(-345+315\right)=-30\cdot20=-600\)

c: \(25\left(27-55\right)-27\left(25-55\right)\)

\(=25\cdot27-25\cdot55-27\cdot25+27\cdot55\)

\(=27\cdot55-25\cdot55=2\cdot55=110\)

d: \(25\cdot\left(-415\right)+9\cdot\left(-15\right)\cdot418\)

\(=-25\cdot415-9\cdot15\cdot418\)

\(=-5\left(5\cdot415+3\cdot9\cdot418\right)\)

\(=-5\left(2075+11286\right)=-5\cdot13361=-66805\)

e: \(5+\left(-8\right)\cdot3\)

=5-24

=-19

a) (-2017)- (28- 2017)

= -2017 -28 +2017

= (-2017 +2017) -28

= 0 -28

= -28

b) (17-299) +(17-26+299)

=17 -229 +17 -25 +229

=(17 +17) -(229 +229) -25

=34 -0 -25

=9

c) - (269 -357) + (269 -357)

=-269 +357 +269 -357

=(-269 +269) +(357 -357)

= 0 +0 =0

d) (123 +345)  + (456 -1230 - (2017 - (-345)))

=123 +345 +456 -1230 -2017 -345

=(345 -345) + (123 -1230) + (456 -2017)

=0 + (-1107) + (--1561)

= -2668

\(B=\left(\frac{3}{17}-\frac{2}{345}+\frac{5}{12}\right)-\left(-\frac{2}{345}+\frac{3}{17}-\frac{1}{12}\right)\)
\(B=\frac{3}{17}-\frac{2}{345}+\frac{5}{12}+\frac{2}{345}-\frac{3}{17}+\frac{1}{12}\)
\(B=\left(\frac{3}{17}-\frac{3}{17}\right)+\left(-\frac{2}{345}+\frac{2}{345}\right)+\frac{5}{12}+\frac{1}{12}=\frac{1}{2}\)

a, - ( 269 - 357 ) + ( 269 - 357 )

= - 269 + 357 + 269 - 357

= ( -269 + 269) + ( 357 - 357)

= 0

b, ( 123 + 345 ) + ( 456 - 123 ) - [ 2017 - ( - 345 ) ]

= 123 + 345 + 456 - 123 - [ 2017 + 345 ]

= 123 + 345 + 456 - 123 - 2017 - 345

= ( 123 - 123) + ( 345 - 345 ) + ( 456 - 2017)

= 0 + 0 + (-1561)

= - 1561

c, ( 17 - 229 ) + ( 17 - 25 + 229 )

= 17 - 229 + 17 - 25 + 229

= ( 17 + 17 ) + ( -229 + 229 ) - 25

= 34 + 0 - 25

=  9

d, ( 125 - 679 + 145 ) - ( 125 - 679 )

= 125 - 679 + 145 - 125 + 679

= ( 125 - 125 ) + (-679 + 679 ) + 145

= 0 + 0 + 145

= 145

1

a, (x + 17)- (24+35)

=x + 17 -24-35

=x+ ( -7) - 35

=x+(-42)

b, (-32) - ( y+ 20) +20

=-32-y-20+20

=-32-y + (-20) + 20

=-32-y + 0

=-32-y

Vậy.......

2.

a.(3567-214)-3567                                                     b.(-2017)-(28-2017)

=3567-214-3567                                                       =-2017-28+2017

=(3567-3567)-214                                                     =(-2017+2017)-28

=0-214                                                                       = 0 -28

=-214                                                                         =-28

c.(269-357)+(269-357)                               d.(123+345)+(456-123)-[2017-(-345)]

=-269-357+269-357                                  =123+345+456-123-[2017+345]

=(-269+269)-(357+357)                            =0+345+456-2017-345

=0-714                                                      =456-2017

=-714                                                        =-1561

Học Tốt

# mui #

1. Đơn giản biểu thức:
a) ( x + 17) - ( 24 + 35)

       x + 17 - 24 - 35

        x + ( -42)

b) ( -32) - ( y + 20) + 20

     - 32  - y - 20 +20

     - 32 - y + 0

     - y - 32

2. Tính nhanh các tổng sau:

a) ( 3567 - 214 ) - 3567

=  3567 - 214 - 3567

=  ( 3567 - 3567 ) - 214

=          0        -   214

=   -214

b) ( -2017) - ( 28 - 2017)

=  -2017 - 28 + 2017

= ( 2017 - 2017 ) -28

= -28

c) -(269 - 357) + ( 269- 357)

= - 269 + 357 + 269 - 357

= ( 269 - 269 ) + ( 357 - 357)

=         0          +        0

= 0