n: =345:(-345)=-1

n, (-15) x (-23) : (-345)

=   345  : (-345)

= -1

o, 36.55 - 185.11 + 121.5

 = 36.11.5 - 5.11.37 + 11.11.5

= 11.5.(36- 37 + 11)

= 11.5.10

= 550

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

a) (-21) + | -50 | + (-29) – | -2016 |

= -21 + 50 - 29 -2016

= (-21 - 29 +50 ) -2016

= -2016 
b) 36 : 32 + 32 . 23 -150 ( xem lại đề nhé )
c) ( 5103 – 5102 – 5101) : ( 599 . 26 – 599)

= ( 1 - 5101 ) : ( 599 . ( 26 - 1 ) ) 

= - 5100 : (599 . 25) 

= \(-\frac{204}{599}\)

a) 23 + 25 + 27 + 29 + 31 + 33 + 35

= 23 + ( 25 + 35 ) + ( 27 + 33 ) + ( 29 + 31 )

= 23 +        60      +      60         +      60

= 23 + 60 x 3

= 23 +    180

= 203

b) 4 . 36 . 25 . 50

=  4 . 4 .9 . 25 . 25 . 2

= 4 . 25 . 4 . 25 . 9 . 2

=   100 . 100     . 9 . 2

= 10 000           . 18

= 180 000

c) 32 . 125 . 3 

= 4 . 8 . 5 . 25 . 3

= 4 . 25 . 8 . 5 . 3

=  100    . 8 . 5 . 3

=      800 . 5 . 3

= 4000 . 3

= 12000

d, 36 . 19 + 36 . 81

= 36 . ( 19 + 81 )

= 36 . 100

= 3600

e, 78 . 31 + 78 . 24 + 78 . 17 + 22 x 72

= 78 . ( 31 + 24  + 17 ) + 22 x 72

= 78 . 72 + 22 . 72

= 72 . ( 78 + 22 )

= 72 . 100

= 7200

A)23+25+27+29+31+33+35

= (33+27)+(25+35)+(29+31)+23

=60+60+60+23

=60x3+23

=180+23

=203

B)4.36.25.50=(36.25).(4.50)

=(4.9.25).(2.2.50)

=(4.25).9 .(2.50).2

=100.9.100.2

=100.(9+2)

=100 .11

=1100

C)32.125.3=(4.8).125.3

=(125.8).(4.3)

=1000.12

=12000

D)36.19.36.81=36.(19+81)

 = 36.100

=3600

E)78.31.+78.24+78.17+22x72=78.31+78.24+78.17+ (16+6).72

=78.31+78.24+78.17+78.16

=78.(31+24+17+16)

=78.88

=6864

a) 58.57+58.150-58.125   

=58.(57+150-125)

=58.    82

=    4756        

b)3².5-2².7+83.2019⁰

=9.5-4.7+83

=45-28+83

=100

c)2019+(-247)+(-53)-2019 

 =(2019-2019)+[ (-247)+(-53)]

0+(-300)

= -300             

d)13.70-50 [(19-3²):2+2³]

=13.70-50[10:2+8]

=13.70-50.13

=13.(70-50)

=13.20

=260

2.

a)x-36:18=12-5   

    x-36:18=6

    x-36=6.18   

     x-36=108

      x=108+36

      x=    144                    

b)92-(17+x)=72

17+x=92-72

17+x=20

x=20-17

x=3

c)720:[41-(2x+5)]=40     

41-(2x+5)=720:40

41-(2x+5)=  18

2x+5=41-18

2x+5=23

2x=23-5

2x=18

x=18:2

x=9                 

d) (x+2)³ -23=41

 (x+2)³ =41+23

 (x+2)³ =64

=> (x+2)³ =4³

=>x+2=4

=>x=4-2

=>x=2

\(a,\left(x-36\right):\left(2\cdot3^2\right)=2^3\cdot3\\ \Leftrightarrow x-36=432\\ x=468\\ b,2^x=32\\ \Leftrightarrow x=5\\ \Leftrightarrow x^3=27\\ \Leftrightarrow x^3=3^3\\ \Leftrightarrow x=3\\ d,1579+\left(625-x\right)=2023\\ \Leftrightarrow x=1579+625-2023\\ \Leftrightarrow x=181\)

A. \(\left(x-36\right):\left(2.3^2\right)=2^3.3\)

\(\left(x-36\right):\left(2.9\right)=8.3\)

\(\left(x-36\right):18=24\)

\(x-36=24.18\)

\(x-36=432\)

\(x=432+36\)

\(x=468\)

B. \(2^x=32\)

\(2^x=2^5\)

\(x=5\)

C. \(x^3=27\)

\(x^3=3^3\)

\(x=3\)

D. \(1579+\left(625-x\right)=2023\)

\(625-x=2023-1579\)

\(625-x=444\)

\(x=625-444\)

\(x=181\)

a) \(\left(x-36\right)\div\left(2\times3^2\right)=2^3\times3\)

\(\left(x-36\right)\div\left(2\times9\right)=8\times3\)

\(\left(x-36\right)\div18=24\)

\(x-36=432\)

\(x=468\)

b) \(2^x=32\)

\(2^x=2^5\)

\(x=5\)

c) \(x^3=27\)

\(x^3=3^3\)

\(x=3\)

d) \(1579+\left(625-x\right)=2023\)

\(\left(625-x\right)=2023-1579\)

\(625-x=444\)

\(x=625-444\)

\(x=181\)

áp dụng kiến thức tính nhanh ý

1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30+31+32+33+34+35+36+37+38+39+40+41+42+43+44+45+46+47+48+49+50=1275

= 1275

=1275

=1245

Có ai rảnh đâu mà đi ngồi cộng ngần đấy số ra.