\(3^2.x+2^2.x=26.2^2-13\\ =>x\left(3^2+2^2\right)=26.4-13\\ =>13x=104-13\\ =>13x=91\\ =>x=91:13\\ =>x=7\)

1;2;4;5;8;10; 20; 25;40;50 ; 100

\(\dfrac{x}{2}=\dfrac{x}{3}\\ =>3x=2x\\ =>3x-2x=0\\ =>x=0\)

x=6.0

Câu 1:

a) 19.63 +36.19+ 19

= 19. ( 63+36+1)

= 19 . 100 =1900

b) 7²- 36 : 3²

= 49 - 36 : 9

= 49 - 4 = 45

c) 4.17.25

= ( 4.25) . 17

= 100.17 = 1700

d) 476 - { 5.[409 - ( 8 .3-21² )] - 1724}

= 476 - { 5. [ 409 - 24- 441)]- 1724}

= 476 - { 5. [ 385 - 441)] - 1724}

= 476 - { 5. -56 - 1724}

= 476 - { -280 - 1724}

= 476 -  ( -2004) = 2480

Câu 2:

a) 41 - ( 2x - 5 ) = 18

2x - 5 = 41 - 18

2x - 5 = 23

2x = 23 + 5 

2x = 28

x = 28 : 2

x = 14

2^x . 4 = 128

2^x = 128 : 4 

2^x = 32

2^x = 2⁵

x + 25 = 40

x = 40 - 25

x = 15

d) 5. (  x + 35 ) = 515 

x + 35 =  515 : 5

x + 35 = 103

x = 103 - 35

x = 68

A) 19.63 + 36.19 + 19

  = 19.( 63+36+1 )

  = 19. 100 = 1900

C) 4.17.25

   = ( 4.25 ) .17

   =   100 .17 = 1700

A = 57 x 16 + 23 x 25 + 16 x 43 - 25 x 13 

A = (57 x16 + 16 x 43) + (23 x 25 - 25 x 13 )

A = 16x ( 57 + 43) + 25x ( 23 - 13)

A = 16 x 100 + 25 x 10

A = 1600 + 250

A = 1850

\(2\left(2x-1\right)^2=50\\ \Rightarrow\left(2x-1\right)^2=50:2=25\\ \Rightarrow\left(2x-1\right)^2=5^2\)

\(\Rightarrow\left[{}\begin{matrix}2x-1=5\\2x-1=-5\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=3\\x=-2\end{matrix}\right.\)

Đs...

`4(x-21)-2=50`

`4(x-21)=50+2=52`

`x-21=52:4=13`

`x=13+21=34`

$4(x-21)-2=50$

$4(x-21)=50+2=52$

$x-21=52:4=13$

$x=13+21=34$

    123x 456456 - 123123 x 456

= 123 x 456 x 1001 - 123 x456 x1001

= 0 

\(6.5.7+8.11=30.7+8.11=2.15.7+2.4.11=2.\left(15.7+4.11\right)⋮2\\ \Rightarrow Hợp.số\)

A = 6.5.7 + 8.11

6⋮ 2;  8⋮ 2 ⇔A ⋮2 ⇔  A  ⋮ 1; 2; A ⇔ A là hợp số