4 + 8 + 12 + ... + 4 * x = 180

 =>  4. ( 1 + 2 + 3 + ... + x) = 180

 =>     1 + 2 + 3 + ... + x     = 180 : 4

 =>      1 + 2 + 3 + ... + x    = 45

 =>     x * ( x + 1 ) : 2          = 45

 =>        x * ( x + 1 )           =  45 * 2 = 90

 =>         x * ( x + 1 )          =   9 * 10

 =>                 x                 =       9. 

      Nếu thấy đúng cho mình xin nha

1: \(\Leftrightarrow x=UCLN\left(24;36;150\right)=6\)

2: \(\Leftrightarrow x\in\left\{24;48;72;...\right\}\)

mà 16<=x<=50

nên \(x\in\left\{24;48\right\}\)

3: \(\Leftrightarrow x\inƯ\left(6\right)\)

mà x>-10

nên \(x\in\left\{1;-1;2;-2;3;-3;6;-6\right\}\)

4: \(\Leftrightarrow x\in BC\left(4;5;8\right)\)

\(\Leftrightarrow x\in\left\{...;-40;0;40;80;120;160;200;...\right\}\)

mà -20<x<180

nên \(x\in\left\{0;40;80;120;160\right\}\)

\(x\) ⋮ 5; \(x\) ⋮ 4; \(x⋮\) 8; - 20 < \(x\) < 180

⇒ \(x\) BC(4; 5; 8)

4 = 2²; 5 = 5; 8 = 2³; BCNN(4;5;8) = 2³.5 = 40

⇒ \(x\) \(\in\) {0; 40; 80; 120; 160; 200; ...;}

Vì -20 < \(x\) < 180 nên \(x\) \(\in\) {0; 40; 80; 120; 160; 200}

\(\frac{12}{26}=\frac{-x}{4}=\frac{21}{y}=\frac{z}{180}\)

\(\Rightarrow\frac{12}{26}=\frac{-x}{4}\Leftrightarrow-x.26=48\Leftrightarrow x=\frac{-24}{13}\)

\(\Rightarrow\frac{12}{26}=\frac{21}{y}\Leftrightarrow12.y=546\Leftrightarrow y=\frac{91}{2}\)

\(\Rightarrow\frac{12}{26}=\frac{z}{180}\Leftrightarrow z.26=2160\Leftrightarrow z=\frac{1080}{13}\)

Vậy : ...

chúc bạn học tốt

x=o,46153846153

y=-0,11538461538

z=-182,000000007

x=-13/16

y=273

z=55/5/13

a 180 -(x + 15) : 4 =80:5       180 - (x + 15) : 4 = 16       180 - ( x + 15) = 16 x 4         180 - ( x + 15 ) = 64       x + 15 = 180 - 64     x + 15 = 116     x= 116 - 15      x = 101

( x + 1 ) x số các số hạng : 2 = 1711

a) 180 - ( x + 15 ) : 4 x 5 = 80 

    180 - ( x + 15 ) = 80 x 4 

    180 - ( x + 15 ) = 320

    x + 15 = 320 - 180

    x + 15 = 140

    x = 140 - 15 

    x = 125 

98775 - 32 x 85

=98775 -2720

=96055

 67500 - 24 x 236

= 67500 -5664

=61836

 568 + 101598 : 287

= 568 +354

=922

6875 + 980 -180  

=7855 -180 

=7675

\(\dfrac{2}{5}+\dfrac{3}{10}-\dfrac{1}{2}\)

\(=\dfrac{7}{10}-\dfrac{1}{2}\)

= \(\dfrac{1}{5}\)

\(\dfrac{8}{11}+\dfrac{8}{33}x\dfrac{3}{4}\)

\(=\dfrac{8}{11}+\dfrac{2}{11}\)

\(=\dfrac{10}{11}\)

\(\dfrac{7}{9}x\dfrac{3}{14}:\dfrac{5}{8}\)

\(=\dfrac{1}{6}:\dfrac{5}{8}\)

\(=\dfrac{1}{6}x\dfrac{8}{5}\)

\(=\dfrac{8}{30}\)

\(=\dfrac{4}{15}\)

\(\dfrac{5}{12}-\dfrac{7}{32}:\dfrac{21}{16}\)

\(=\dfrac{5}{12}-\dfrac{7}{32}x\dfrac{16}{21}\)

\(=\dfrac{5}{12}-\dfrac{1}{6}\)

\(=\dfrac{5}{12}-\dfrac{2}{12}\)

\(=\dfrac{3}{12}=\dfrac{1}{4}\)

_{Tín hịu cầu kíu :>>}

dễ thương quá minion 

d, X/8*32+X/3*18-X/5*10=120

   X*32/8+X*18/3-X*10/5=120

  32X/8+18X/3-10X/5=120

  4X+6X-2X=120

  8X=120

 X=120/8

X=15

a, ( 25 * 12 - X - 25 ) : 25 = 4

( 25 * 12 - x - 25 )           = 4 * 25 

( 25 * 12 - x - 25 )           = 100

300 - x - 25                    = 100

300 - x                           = 100 + 25

300 - x                           = 125

x                                   = 300 - 125

x                                   = 175

- x×3=12

x=12:3

x=4

- 4×x=8

x=8:4

x=2

- x×4=28

x=28:4

x=7

a) x : 4 = 8

x = 8 × 4

x = 32

b) 4 × x = 12 + 8

4 × x = 20

x = 20 : 4

x = 5

c) 30 : x = 14 + 16

30 : x = 30

x = 30 : 30

x = 1