`@` `\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) 7,63 x 12,47 + 12,47 x 2,37 - 2,5 x 40

= 12,47 x (7,63 + 2,37) - 100

= 12,43 x 10 - 100

= 124,3 - 100

= 24,3

b) \(\dfrac{7.5.12}{15.8.4}\) = \(\dfrac{7.5.3.2.2}{3.5.2.2.2.2.2}\) = \(\dfrac{7}{4.2}\)= \(\dfrac{7}{8}\)

(P/s: Dấu "." là dấu x (nhân) đó nha! :>>>)

Chúc bạn học tốt!! ^^

Bài 2: 

a: =>x-35=-23

=>x=12

b: =>|x-8|=13

=>x-8=13 hoặc x-8=-13

=>x=21 hoặc x=-5

Bài 1: 

a: =42-98-42+12-12=-98

b: =10x4x3x(-25)=40x(-25)x3=-1000x3=-3000

2:

b=2000*2004

=(2002-2)*(2002+2)

=2002^2-4

=>b<a

1:

a: \(=8\cdot9\left(14+17+19\right)=72\cdot50=3600\)

Bài 1:

\(8\times9\times14+6\times17\times12+19\times4\times18\)

\(=8\times9\times14+3\times2\times17\times2\times2\times3+19\times4\times2\times9\)

\(=8\times9\times14+17\times8\times9+19\times8\times9\)

\(=8\times9\times\left(14+17+19\right)\)

\(=8\times9\times50\)

\(=72\times5\times10\)

\(=360\times10\)

\(=3600\)

Bài 2:

Ta có:

\(a=2022\times2022\)

Và: \(b=2000\times2004\)

Mà: \(2022>2000,2022>2004\)

\(\Rightarrow2022\times2022>2000\times2004\)

\(\Rightarrow a>b\)

Ta gọi vế \(\left(12\cdot2+12\cdot4+12\cdot6\right)\)là vế \(\left(1\right)\)

Ta gọi vế \(\left(2+4+...+12+14\right)\)là vế \(\left(2\right)\)

\(\left(1\right):\)\(12\cdot\left(2+4+6\right)=12\cdot12=144\)

\(\left(2\right):\)\(\frac{\left(14-2\right)}{2}+1=7\)( số )\(=\left(14+2\right)\cdot\frac{7}{2}=28\)

Vậy ta có \(:\)

\(A=\frac{144}{56}=2.5714\)

Đáp số : \(2.5714\)

A)    (12 x 2 + 12 x 4 + 12 x 6) : ( 2 + 4 + 6 + ... + 12 + 14)
     = [12 x ( 2 + 4 - 6 )] : ( 2 + 4 + 6 + ... + 12 + 14)
     = [12 x 0 ] : ( 2 + 4 + 6 + ... + 12 + 14)
     = 0 : ( 2 + 4 + 6 + ... + 12 + 14)
     = 0 
B)    37 x 49 + 37 x 2 x 25 + 37 
     = 37 x (49 + 2 x 25 + 1)
     = 37 x 100 
     = 3700

Học dỏi nha :)))
~ Good luck ~

Sai cái dì mà mí người k sai nhiều quá v ?? :D ?? 

Sai cái dề :D ???????

2 x 18 x 14 + 3 x 17 x 12 + 4 x 69 x 6

= (2 x 18) x 14 + (3 x 12) x 17 + (4 x 6) x 69

= 36 x (14 + 17 + 69)

= 36 x 100

= 3600

\(2.18.14+3.17.12+4.69.6\)

\(=\left(2.18\right).14+\left(3.12\right).17+\left(4.6\right).69\)

\(=36.14+36.17+24.69\)

\(=36.\left(14+17\right)+24.69\)

\(=36.31+24.69\)

\(=4.9.31+4.6.69\)

\(=4.\left(9.31+6.69\right)\)

\(=4.\left(279+414\right)\)

\(=4.693\)

\(=2772\)

Jennie Kim làm sai từ dòng thứ 3 rồi nha bn

~ Rất vui vì giúp đc bn ~

a.3-(-12+3)+x=x-(-12-10)

<=> 3+9+x=x+22

<=>x-x=22-3-9

<=> 0x=10

b,2-x=14-(x+4)

<=>2-x=14-x-4)

<=>x-x=14-4-2

<=>0x=8

c.x-12=14+(6-x)

<=>x-12=14+6-x

<=>x+x=14+6+12

<=>0x=32