x + 2x + 3x + ...+ 9x = 1800

x(1+2+3+...+9)=1800

45x=1800

x=1800:45

x=40

Vậy, x=40

Ta có:

\(x+2x+3x+...+9x=1800\)

\(45x=1800\)

\(x=\frac{1800}{45}=40\)

\(x+2x+3x+....+9x=990.\)

\(\Rightarrow x.\left(1+2+3+....+9\right)=990\)

\(\Rightarrow x.45=990\)

\(\Rightarrow x=990:45\)

\(\Rightarrow x=22\)

X duoc xuat hien so lan la:

            1+2+3+4+5+6+7+8+9=45

x=990÷45=22

                 ĐS:22

x+2x+3x+...+9x=4593

x(1+2+3+...+9)=4593

x.45=4593

x=4593:45

x=102,666667

ai diễn giải ra cho ****

Ta có;

x+2x+3x+4x+...+9x=1000-100

=>x+2x+3x+4x+...+9x=900

=>(1+2+3+4+....+9)x=900

=>[(1+9).9:2]x=900

=>45x=900

x=900:45=20

cho tớ đúng nha

Ta có;

x+2x+3x+4x+...+9x=1000-100

=>x+2x+3x+4x+...+9x=900

=>(1+2+3+4+....+9)x=900

=>45x=900

x=900:45=20

=>x.(1+2+3+....+9)=459-3^2=459-9=450

=>x.45=450

=>x=10

x+ 2x + 3x +...+ 9x = 459 -\(3^2\)

x+ 2x + 3x +...+ 9x =459 -9

x+ 2x + 3x +...+ 9x =450

x.(1+2+3+...+9) = 450

x. 45 = 450

      x = 450 : 45

     x = 10

     HT!!!

a) 

<=> 3x - 3 + x - 2 = 2x - 2 - x + 1

<=> 3x + x - 2x + x = -2 + 1 + 3 + 2

<=>    3x               = 4

<=>   x                  = 4/3

Các câu sau làm tương tự

\(\left(3x-3\right)+\left(x-2\right)=\left(2x-2\right)-\left(x-1\right)\)

<=>   \(3x-3+x-2=2x-2-x+1\)

<=>  \(4x-5=x-1\)

<=> \(3x=4\)

<=>  \(x=\frac{4}{3}\)

Vậy....

264+12x=1800

12x=1536

x=128

(x+73):19=321

x+73=6099

x=6026

2x+3x+4x=18

9x=18

x=2

10<2x<20

=>5<x<10

x=6,7,8,9

\(264+12x=1800\)

\(\Leftrightarrow12x=1536\)

\(\Leftrightarrow x=128\)

==============

\(\left(x+73\right):19=321\)

\(\Leftrightarrow x+73=6099\)

\(\Leftrightarrow x=6026\)

===============

\(2x+3x+4x=18\)

\(\Leftrightarrow x.\left(2+3+4\right)=18\)

\(\Leftrightarrow x.9=18\)

\(\Leftrightarrow x=2\)

================

\(10< 2x< 20\)

..................................

\(2x=12\Leftrightarrow x=6\)

\(2x=14\Leftrightarrow x=7\)

\(2x=16\Leftrightarrow x=8\)

\(2x=18\Leftrightarrow x=9\)

\(x\in\left\{6;7;8;9\right\}\)

bn hỏi 1 lần thôi đừng đăng nhiều chật lắm

12x = 1800 - 264

12x = 1536

x = 1536 : 12

x = 128

( x + 73 ) : 19 = 321

( x + 73 ) = 321 x 19

 x + 73 = 6099

x = 6099 - 73

x = 6026

2x + 3x + 4x = 18 

x . ( 2 + 3 + 4 ) = 18

x .          9          = 18

x = 18 : 9

x = 2

10 < 2x < 20

x = 6 ; 7 ; 8 ; 9