Tìm x thuoc z:

1) \(26-\left|x+9\right|=-13\)

\(\Leftrightarrow\left|x+9\right|=26-\left(-13\right)\)

\(\Leftrightarrow\left|x+9\right|=39\)

\(\Leftrightarrow\left[{}\begin{matrix}x+9=39\\x+9=-39\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=39-9=30\\x=-39-9=-48\end{matrix}\right.\)

Vậy: \(x\in\left\{30;-48\right\}\)

2) \(\left|x+7\right|-13=25\)

\(\Leftrightarrow\left|x+7\right|=25+13=38\)

\(\Leftrightarrow x+7\in\left\{38;-38\right\}\)

\(\Leftrightarrow x\in\left\{31;-45\right\}\)

Vậy:.................

tim x biet

\(1)123-3.\left(x+4\right)=23\)

\(\Leftrightarrow3\left(x+4\right)=123-23\)

\(\Leftrightarrow3\left(x+4\right)=100\)

\(\Leftrightarrow x+4=\frac{100}{3}\)

\(\Leftrightarrow x=\frac{100}{3}-4=\frac{100-12}{3}=\frac{88}{3}\)

Vậy:................

2) Tương tự

(2x - 4)³ = 8

(2x - 4)³ = 2³

2x - 4 = 2

2x = 2 + 4

2x = 6

x = 6 : 2

x = 3

\(\frac{720}{41-\left(2x-5\right)}=2^3\times5\)

\(\frac{720}{41-2x+5}=8\times5\)

\(46-2x=\frac{720}{40}\)

\(2x=46-18\)

2x = 28

x = 28 : 2

x = 14

vế a thiếu kết quả kìa bạn

b) => 364:x+15.x:x=697:17

=> 364:x+15=41

=> 364:x=41-15

=> 364:x=26

=> x=364:26

=> x= 14

a)  720:[41-{2.x-5}]=40

=> 41-(2.x-5)=720:40

=> 2.x-5=41-18

=> 2.x=23+5

=> x=28:2

=> x=14

a)13/17 < 15/19

a) 2/3 x X + 3/4 = 3

          2/3 x X    = 3 - 3/4

          2/3 x X    = 9/4

                   X    = 9/4 : 2/3

                   X    = 27/8

a. Ta có : \(\frac{13}{17}=\frac{247}{323};\frac{15}{19}=\frac{255}{323}\)

Vì 255 > 247 nên 247/323 < 255/323 

Hay \(\frac{13}{17}< \frac{15}{19}\)

b. \(\frac{2}{3}\times x+\frac{3}{4}=3\)

\(\frac{2}{3}\times x=3-\frac{3}{4}\)

\(\frac{2}{3}\times x=\frac{9}{4}\)

\(x=\frac{9}{4}:\frac{2}{3}\)

\(x=\frac{27}{8}\)

c. \(720:\left[41-\left(2\times x-5\right)\right]=120\)

\(\left[41-\left(2\times x-5\right)\right]=720:120\)

\(41-\left(2\times x-5\right)=6\)

\(2\times x-5=35\)

\(2\times x=40\)

\(x=20\)

a)\(\frac{13}{17}>\frac{15}{19}\)

b)\(720\div[41-(2x\times5)]=120\)                                 c)\(\frac{2}{3}\times x+\frac{3}{4}=3\)

   \(41-(2x\times5)=270\div120\)                                          \(\frac{2}{3}\times x=3-\frac{3}{4}\)

    \(41-(2x-5)=6\)                                                               \(\frac{2}{3}\times x=\frac{9}{4}\)

     \(2x-5=41-6\)                                                                     \(x=\frac{9}{4}\div\frac{2}{3}\)

     \(2x-5=35\)                                                                                \(x=\frac{9}{4}\times\frac{3}{2}\)

     \(2x=35+5\)                                                                                \(x=\frac{27}{8}\)

      \(2x=40\)

      \(x=40\div2\)

      \(x=20\)

a) \(\left[\left(4x+28\right).3+55\right]:5=35\)

\(\Leftrightarrow\left(4x+28\right).3+55=35.5\)

\(\Leftrightarrow\left(4x+28\right).3+55=175\)

\(\Leftrightarrow\left(4x+28\right).3=175-55\)

\(\Leftrightarrow\left(4x+28\right).3=120\)

\(\Leftrightarrow4x+28=120:3\)

\(\Leftrightarrow4x+28=40\)

\(\Leftrightarrow4x=40-28\)

\(\Leftrightarrow4x=12\)

\(\Leftrightarrow x=12:4\)

\(\Leftrightarrow x=3\)

Vậy \(x=3\)

b) \(\left(12x-4^3\right).8^3=4.8^4\)

\(\Leftrightarrow12x-4^3=4.8^4:8^3\)

\(\Leftrightarrow12x-4^3=4.8^{4-3}\)

\(\Leftrightarrow12x-4^3=4.8\)

\(\Leftrightarrow12x-4^3=32\)

\(\Leftrightarrow12x-64=32\)

\(\Leftrightarrow12x=32+64\)

\(\Leftrightarrow12x=96\)

\(\Leftrightarrow x=96:12\)

\(\Leftrightarrow x=8\)

Vậy \(x=8\)

c) \(720:\left[41-\left(2x-5\right)\right]=2^3.5\)

\(\Leftrightarrow720:\left[41-\left(2x-5\right)\right]=8.5\)

\(\Leftrightarrow720:\left[41-\left(2x-5\right)\right]=40\)

\(\Leftrightarrow41-\left(2x-5\right)=720:40\)

\(\Leftrightarrow41-\left(2x-5\right)=18\)

\(\Leftrightarrow2x-5=41-18\)

\(\Leftrightarrow2x-5=23\)

\(\Leftrightarrow2x=23+5\)

\(\Leftrightarrow2x=28\)

\(\Leftrightarrow x=28:2\)

\(\Leftrightarrow x=14\)

Vậy \(x=14\)

720 : [ 41 - ( 2 x x -5 ) =120

41 - ( 2 x x - 5 ) = 720 : 120

41 - ( 2 x \(x\) -5 ) =6

2 x \(x\) -5 = 41 - 6

2 x \(x\) - 5 = 35

2 x \(x\) = 35+5

2 x \(x\)=40

\(x\) = 40 : 2 = 20

Vậy x = 20

Ủng hộ nhé ^^

720 : [ 41 - ( 2 x X - 5 ) ] = 120

           41 - ( 2 x X - 5 )   = 720 : 120

           41 - ( 2 x X - 5 )   = 6

                    2 x X - 5      = 41 - 6 

                    2 x X - 5      = 35

                    2 x X           = 35 - 5

                    2 x X           = 30

                          X           = 30 : 2

                          X           = 15

Học tốt nhé bạn !

720÷[41-(2×x-5)]=120

41-(2.x-5)=720:120

41-(2.x-5)=6

2.x-5=41-6

2.x-5=35

2.x=35+5

2.x=40

x=40:2

x=20

Vậy.............................................

720 : [ 41 - ( 2x-5)] = 2^3 .5

=> 720 :[ 41- (2x-5)] = 40

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

=> 2x -5 = 23

=> 2x = 28

=> x=14

255 - 21 . 5 . ( 198 : 11 - 8 )

= 255 - 105 . ( 18 - 8 )

= 255 - 105 . 10

= 255 - 1050

= -795

720 : [ 41 - ( 2 . x . 5 ) ] = 2³ . 5

720 : [ 41 - ( 10 . x ) ] = 40

41 - ( 10 . x ) = 720 : 40

41 - ( 10 . x ) = 18

10 . x = 41 - 18

10 . x = 23

x = 23/10

Tinh nhanh ( neu co ) :

255 - 21 . 5 . ( 198 : 11 - 8 )

= 255 - 21 . 5 . ( 18 - 8 )

=255 - 21 . 5 . 10

=255 - 1050

= -795