`a, 232 - ( 581 + 132 -331)`

`= 232 - 581 - 132 +331`

`= (232-132) +(-581 + 331)`

`= 100 -250`

`=-150`

`b, [12+ (-57)] - [-57-(-12)]`

`= 12+ (-57) - (-57+12)`

`= 12+ (-57) + 57 -12`

`= (12-12) + (-57+57)`

`= 0+0`

`=0`

`a)232-(581+132-331)`

`=232-581-132+331`

`=(232-132)-(581-331)`

`=100-250`

`=-150`

`b)[12+(-57)]-[-57-(-12)]`

`=(12-57)-(-57+12)`

`=12-57+57-12`

`=(12-12)-(57-57)`

`=0-0`

`=0`

a) 232 - (581 + 132 - 331)

= 232 - 581 - 132 + 331

= (232 - 132) - (581 - 331)

= 100 - 250

= -(250 - 100)

= -150

b) [12 + (-57)] - [-57 - (-12)]

= 12 - 57 + 57 - 12

= (12 - 12) + (57 - 57)

= 0 + 0

= 0

a) \(232-\left(581+132-331\right)\)

\(=232-581-132+331\)

\(=\left(232-132\right)+\left(331-581\right)\)

\(=100-250\)

\(=-150\)

b) \(\left[12+\left(-57\right)\right]-\left[-57-\left(-12\right)\right]\)

\(=12-57+57-12\)

\(=\left(12-12\right)+\left(57-57\right)\)

\(=0+0\)

\(=0\)

a) 232 - ( 581 + 132 - 331 )

= 232 - 581 - 132 + 331

= ( 232 - 132 ) - ( 581 - 331 )

= 100 - 250

= -150

a) 232 – (581 + 132 – 331)

= 232 – 581 – 132 + 331

= (232 – 132) – (581 – 331)

= 100 – 250

= -150

b) [12 + (-57)] - [- 57 - (-12)] 

= (12 – 57) – (- 57 + 12)

= 12 - 57 + 57 - 12 

= (12 – 12) + (57 – 57)

= 0 + 0 

= 0

a, -321 + (-29 ) - 142 - (-72) = -321 - 29 - 142 + 72 = -420.

b, 214 - (-36) + (-305) = 214 + 36 - 305 = -55.

c, 232 - (581 + 132 - 331) = 232 - 581 - 132 + 331 = -150.

d, [ 12+ (-57)] - [-57 -  (-12) = 12 - 57 + 57 - 12 = 0.

Bài 3.21:

b: =28+19-28-32+57

=76-32

=44

`@` `\text {Ans}`

`\downarrow`

`1,`

`a)`

`5 \times 72 \times 10 \times 2`

`= 5 \times 2 \times 10 \times 72`

`= 10 \times 10 \times 72`

`= 100 \times 72`

`= 7200`

`b)`

`40 \times 125`

`= 4 \times 10 \times 25 \times 5`

`= (5 \times 10) \times (4 \times 25)`

`= 50 \times 100`

`= 5000`

`c)`

`4 \times 2021 \times 25`

`= (4 \times 25) \times 2021`

`= 100 \times 2021`

`= 202100`

`d)`

`16 \times 6 \times 25`

`= 4 \times 4 \times 6 \times 25`

`= (4 \times 25) \times 4 \times 6`

`= 100 \times 24`

`= 2400`

`2,`

`a)`

`24 \times 57 + 43 \times 24`

`= 24 \times (57+43)`

`= 24 \times 100`

`= 2400`

`b)`

`12 \times 19 + 80 \times 12 +12`

`= 12 \times (19 + 80 + 1)`

`= 12 \times 100`

`= 1200`

`c)`

`(36 \times 15 \times 169) \div (5 \times 18 \times 13)`

`= 36 \times 15 \times 169 \div 5 \div 18 \div 13`

`= 6 \times 6 \times 3 \times 5 \times 13 \times 13 \div 5 \div 3 \times 6 \div 13`

`= (6 \div 6) \times (3 \div 3) \times (5 \div 5) \times (13 \div 13) \times 6 \times 13`

`= 6 \times 13`

`= 78`

`d)`

`(44 \times 52 \times 60) \div ( 11 \times 13 \times 15)`

`= 44 \times 52 \times 60 \div 11 \div 13 \div 15`

`= 4 \times 11 \times 13 \times 4 \times 15 \times 4 \div 11 \div 13 \div 15`

`= (11 \div 11) \times (13 \div 13) \times (15 \div 15) \times 4 \times 4 \times`

`= 4 \times 4 \times 4`

`= 64`

`3,`

`a)`

`x - 280 \div 35 = 5 \times 54`

`x - 8 = 270`

`x = 270 + 8`

`x = 278`

`b)`

`(x - 280) \div 35 = 54 \div 4`

`(x - 280) \div 35 = 13,5`

`x - 280 = 13,5 \times 35`

`x - 280 = 472,5`

`x = 472,5 + 280`

`x = 752,5`

`c)`

`(x - 128 + 20) \div 192 = 0`

`x - 128 + 20 = 0 \times 192`

`x - 128 + 20 = 0`

`x - 108 = 0`

`x = 0 + 108`

`x = 108`

`d)`

`4 \times (x + 200) = 460 + 85 \times 4`

`4 \times (x+200) = 460 + 340`

`4 \times (x+200) = 800`

`x + 200 = 800 \div 4`

`x + 200 = 200`

`x = 200 - 200`

`x = 0`

`4,`

`a)`

`7/12 - 5/12`

`= (7 - 5)/12`

`= 2/12`

`= 1/6`

`b)`

`8/11 + 19/11`

`= (8+19)/11`

`= 27/11`

`c)`

`3/8 + 5/12`

`= 9/24 + 10/24`

`= 19/24`

`d)`

`3/4 + 7/12`

`= 9/12 + 7/12`

`= 16/12`

`= 4/3`

`5,`

`a)`

`x - 6/7 = 5/2`

`x = 5/2 + 6/7`

`x = 47/14`

`b)`

`12/7 \div x + 2/3 = 7/5`

`12/7 \div x = 7/5 - 2/3`

`12/7 \div x = 11/15`

`x = 12/7 \div 11/15`

`x = 180/77`

`@` `\text {Kaizuu lv uuu}`

a: -23-12=-(23+12)=-35

a: -100-12=-(100+12)=-112

a: -123-20=-(123+20)=-143

a: 43-(-53)=43+53=96

a: 14-(-20)=14+20=34

a: -15-(-17)=-15+17=17-15=2

a: 143-(-123)=143+123=266

b: 12-(5-7)=12-(-2)=12+2=14

b: 15-(-9)-4=11+9=20

b: -17-(8-25)=-17-8+25=-25+25=0

b: -5+10-12-5=(10-5-5)-12=0-12=-12

b: (1456+23)-1456=1456-1456+23=0+23=23

b: (2354-45)-2354=2354-45-2354=-45

b: -2021-(57-2021)=-2021-57+2021=-57

c: 283+581-282-531=(283-282)+(581-531)=50+1=51

c: 3758+57-3769-66

=(3758-3769)+(57-66)

=(-11)+(-9)

=-(11+9)

=-20

c: 2575+37-2575+29

=37+29

=66

c: 17+33+(-37)+(-33)

=(17-37)+(33-33)

=0+(-20)

=-20

c: -4+(-10)+25+(-11)

=(-4-10-11)+25

=25-25

=0

c: 42-69+17+(-42)-17

=(42-42)+(17-17)+(-69)

=-69

c: (-2)+(-370)+(-8)+370

=(-2-8)+(-370+370)

=-10+0

=-10

a) = 10 . (-4) + 24. 4

    = 10.(-4) + 96

    = 56

Ở dưới mình nhầm nha hihi

= -800

a: =4700

c: =1900

các bn tính từng bước nhé

a, = 47 . ( 36 + 64 )

= 47 . 100 = 4700

b,  = -43 + 1315 - 126 - 1315 - 57

= ( - 43 - 57 ) - 126 

= - 100 - 126

 = -226

c, = 19 .  ( 35 - 2 + 67 )

= 19 . 100 = 1900

d, = -25 + 117 - 117 + 25

= 0