\(a,x.\left(x+3\right)=0\)

\(\Rightarrow\orbr{\begin{cases}x=0\\x+3=0\end{cases}\Rightarrow\orbr{\begin{cases}x=0\\x=-3\end{cases}}}\)

\(b,30.\left(x+2\right)-6\left(x-5\right)-24x=100\)

\(30x+60-6x-30-24x=100\)

\(x.\left(30+60-6-30-24\right)=100\)

\(x.30=100\)

\(x=\frac{10}{3}\)

72x(28-49)+28x(-49-72)

=72x(-21)+28x(-121)

=-1512+(-3388)

=-49900

Có 2 cách hiểu 

+ ) 72x( 28 - 49 ) + 28x( -49 - 72)

= 72x . 28 - 72x . 49 - 28x . 49 - 28x . 72 

= -72x . 49 - 28x . 49

= 49 . ( - 100x )

+) 72 . ( 28 - 49 ) + 28 . ( -49 - 72 )

= 72 . 28 - 72 . 49 -28 . 49 - 28 . 72

= -72 . 49 -28 . 49

= 49 . ( -100 ) = -4900

a)    \(\left(-25\right).5.\left(-4\right).2\)

\(=\left[\left(-25\right).\left(-4\right)\right].\left(2.5\right)\)

\(=100.10=1000\)

b)   \(\left(-456\right)-\left(67-456\right)\)

\(=-456-67+456\)

\(=\left(456-456\right)-67\)

\(=67\)

a) ((-25).(-4)).5.2

=100.10

=1000

b) (-456)-67+456

=(-456)+(-67)+456

=0+-(-67)

=-67

c)78.45+-145.78

=78.(45+145)

=78.190

=Tự làm

a) (-25).5.(-4).2

= 5 . ( -4 ) . ( -25 ) . 2

= -20 . ( - 50 )

= 100

b) (-456) - (67 - 456)

= -456 - 67 + 456

= -456 + 456 - 67

= -67

c) 78.45+145.(-78)

= 78 . 45 + ( - 145 ) . 78

= 78 . ( -145 + 45 )

= 78 . 100

= 7800

d) 38.( 62-75) + 62.(-75 - 38)

= 38 . 62 - 38 . 75 + 62 . ( - 75 ) - 62 . 38

= 38 . 62 - 62 . 38 + 38 . 75 + 62 . ( - 75 )

= 0 + 38 . 75 + ( - 62 ) . 75

= 75 . ( - 62 + 38 )

= 75 . ( - 24 )

= - 1800

a) 125.(-4).(-8).7

= 125 . ( - 8 ) . ( - 4 ) . 7

= 1000 . ( - 28 )

= - 28000

c) 72.( 28 - 49) + 28. ( -49 - 72)

= 72 . 28 - 72 . 49 + 28 . ( - 49 ) - 28 . 72

= 72 . 28 - 28 . 72 + 72 . 49 + 28 . ( - 49 )

= 0 + 72 . 49 + ( - 28 ) . 49

= 49 . ( -28 + 72 )

= 49 . 44

= 2156

45-58+(-45)+(+58)-3=45-58-45+58-3=(45-45)+(58-58)-3=-3

(-57)-(-12)+3-(-57)=-57+12+3+57=(-57+57)+12+3=15

-(-24)-(-30)+(-24)-30+8=24+30-24-30+8=(24-24)+(30-30)+8=8

-(-12)+(+19)-(+12)+8-19=12+19-12+8-19=(12-12)+(19-19)+8=8

47-(-53)+(-47)-(+53)=47+53-47-53=(47-47)+(53-53)=0

-(+28)+32-(-28)+(-34)=-28+32+28-34=(-28+28)-(34-32)=-2

15-(+72)+(-15)+(+72)=15-72-15+72=(15-15)+(72-72)=0

20-(+46)+(-25)-(-46)=20-46-25+46=(20-25)+(46-46)=-5

28-(-32)+(-28)-32+5=28+32-28-32+5=(28-28)+(32-32)+5=5

-75+(-49)+(+75)+49-12=-75-49+75+49-12=(-75+75)+(49-49)-12=-12

\(...=45-58-45+58-3=-3\)

\(...=-57+12+3+57=15\)

\(...=24+30-24-30+8=8\)

\(...=12+19-12+8-19=8\)

\(...=47+53-47-53=0\)

\(...=-28+32+28-34=-2\)

\(...=15-72-15+72=0\)

\(...=20-46-25+46=-5\)

\(=...28+32-28-32+5=5\)

\(...=-75-49+75+49-12=-12\)

A)

  -65.(87-17)-87.(17-65)

=-65.87-(-65).17-87.17-87.(-65)

=-(-65).17-87.17

=65.17-87.17

=17.(65-87)

=17.(-22)

=-374

B)

   72.(28-49)+28.(-49-72)

= 72.28-72.49+28.(-49)-28.72

= -72.49+28.(-49)

=  72.(-49)+28.(-49)

=  (-49).(72+28)

=  -49.100

=-4900

C)

18-(-27)+63-(63+27)

=  18+27+63-63-27

=  45+0-27

=  45+(-27)

=45-27

=18

KICK MÌNH NHÁ

Viết rõ ràng chi tiết hộ mik nhé

1. a, 35x67+35x33=35x100=3500

b,8x39x125=8x125x39=1000x39=39000

5. a, ( -15)-|-7|=(-15)-7=-18

b, |-15|-|18|=15-18=-3

X+(-72)=(-28)+(-72)=-100

1.thực hiện phép tính ( hợp lý nếu có thể)         
a) 35. 67 + 35. 33 = 35 . ( 67 + 33 ) = 33 . 100 = 3300            

b) 8.39.125 = ( 8 . 125 ) . 39 = 1000 . 39 = 39000           
a) 3.(15 − 5)2 − 215: 213 = 3.10.2-215:213 = 60 - 1,00... = (bạn tự tính)     

b) 2.(3.52 – 12) =2.(156-12)=2.144=288

c) 52 − 24 : 23 =52-1,043478261 =51,043478261    
a )2340 : [5. 89 - (125 + 5 . 72) + 5 . 11]  

= 2340 : [445-(125+360)+55]

= 2340 : [445-485+55]

= 2340:15

=156

b) 30: {20- [5 + (5 – 2 )2]}=30:{20-[5+3.2]}=30:{20-11}=30:9=3,(3)
a) (−7) + (− 5) =-12

b) 2013 + [ 340 + ( − 2013)]=2013+340+(-2013)=[2013+(-2013)]+340=0+340=340   
a) (– 15) – | − 7 |;      =-15-7=-22

b) | − 15| − | 18 | =15-18=-3
Tính giá trị của biểu thức: x + (−72), biết x = − 28.

Thay x=-28 vào x+(-72) ta được:

=> -28+(-72)=-100

a) ( -12 ) + ( - 9 ) + 121 + | -20 | 

= ( - 21 ) + 121 + 20 

= [ ( - 21) + 121 ] + 20 

= 100 + 20 

= 120

b) 49.125 - 49 .25 

= 49 .( 125 -25 )

= 49. 100 

 = 4900 

c) 20 -[ 30 - ( 5- 1)² ]

= 20 - ( 30 - 4² )

= 20 -  ( 30 - 16 )

 = 20 - 14 

= 6 

d) 28 . 76 + 44.28 -28.20 

= 28 .( 76 + 44 -20)

 = 28 . 100

= 2800

a) \(=\left(\left(-\frac{1}{4}-\frac{5}{3}\right)+\frac{7}{33}\right)-\left(-\frac{15}{12}+\frac{6}{11}-\frac{48}{49}\right)\)

\(=\left(-\frac{23}{12}+\frac{7}{33}\right)+\frac{15}{12}-\frac{6}{11}+\frac{48}{49}\)

\(=\left(-\frac{23}{12}+\frac{15}{12}\right)+\left(\frac{9}{33}-\frac{6}{11}\right)+\frac{48}{49}\)

\(=-\frac{2}{3}-\frac{3}{11}+\frac{48}{49}\)

\(=\frac{65}{1617}\)

b) \(=\frac{11}{125}+\left(-\frac{17}{18}+\frac{4}{9}\right)+\left(-\frac{5}{7}+\frac{17}{14}\right)\)

\(=\frac{11}{125}-\frac{1}{2}+\frac{1}{2}\)

\(=\frac{11}{125}\)

tính từng cái là đc

cau a em

1.a) 4.(12+88) = 4.100=400

b)7²- 6 .[2.8:8 ]=7²-6.[16:8]=7²-6 .2= 49-12=37  ( tui ko chắc lắm )

2.a) x=26-11=15 

b) (4x-15)³=5³ 

4x-15=5 

4x= 5+15

4x=20

vậy x = 20

Bài 2: 

a: Ta có: x+11=26

nên x=15

b: Ta có: \(\left(4x-15\right)^3=125\)

\(\Leftrightarrow4x-15=5\)

hay x=5