a) 32 : (3.x - 2) = 8

3x - 2 = 32 : 8

3x - 2 = 4

3x = 4 + 2

3x = 6

x = 6 : 3

x = 2

b) 75 : (x - 18) = 25

x - 18 = 75 : 25

x - 18 = 3

x = 3 + 18

x = 21

c) (15 - 6.x) . 243 = 729

15 - 6x = 729 : 243

15 - 6x = 3

6x = 15 - 3

6x = 12

x = 12 : 6

x = 2

d) 4.(x - 12) + 9 = 17

4(x - 12) = 17 - 9

4(x - 12) = 8

x - 12 = 8 : 4

x - 12 = 2

x = 2 + 12

x = 14

e) 20 - 2.(x + 4) = 4

2(x + 4) = 20 - 4

2(x + 4) = 16

x + 4 = 16 : 2

x + 4 = 8

x = 8 : 2

x = 4

`32: ( 3xx x -2)=8`

`3xx x-2=32:8`

`3xx x-2=4`

`3 xx x=4+2`

`3xx x=6`

`x=6:3`

`x=2`

__

`75 : (x-18) =25`

`x-18=75:25`

`x-18= 3`

`x=3+18`

`x=21`

__

`(15-6 xx x ) xx 243 =729`

`15-6 xx x = 729 : 243`

`15-6 xx x = 3`

`6 xx x=15-3`

`6 xx x=12`

`x=12:6`

`x=2`

__

`4 xx (x-12)+9=17`

`4 xx (x-12)=17-9`

`4 xx (x-12)= 8`

`x-12=8:4`

`x-12=2`

`x=2+12`

`x=14`

__

`20-2xx(x+4)=4`

`2xx(x+4)=20-4`

`2xx(x+4)=16`

`x+4=16:2`

`x+4=8`

`x=8-4`

`x=4`

\(a,32:\left(3\times X-2\right)=8\\ 3\times X-2=32:8=4\\ 3\times X=4+2=6\\ X=\dfrac{6}{3}=2\\ Vậy:X=2\\ ---\\ b,75:\left(X-18\right)=25\\ X-18=75:25=3\\ X=3+18=21\\ Vậy:X=21\\ ---\\ c,\left(15-6\times X\right)\times243=729\\ 15-6\times X=729:243=3\\ 6\times X=15-3=12\\ X=\dfrac{12}{6}=2\\ Vậy:X=2\\ ---\\ d,4\times\left(X-12\right)+9=17\\ 4\times\left(X-12\right)=17-9=8\\ X-12=8:4=2\\ X=2+12=14\\ Vậy:X=14\\ ---\\ e,20-2\times\left(X+4+4\right)=4\\ 2\times\left(X+4\right)=20-4=16\\ X+4=16:2=8\\ X=8-4=4\\ Vậy:X=4\)

\(a,\Leftrightarrow x^2-x-x^2+4x-4=2\\ \Leftrightarrow3x=6\Leftrightarrow x=2\\ b,\Leftrightarrow\left(x-3\right)\left(x+3\right)-\left(x-3\right)\left(6-x\right)=0\\ \Leftrightarrow\left(x-3\right)\left(x+3-6+x\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=3\\x=\dfrac{3}{2}\end{matrix}\right.\\ c,\Leftrightarrow x^2+2x-3x-6=0\\ \Leftrightarrow\left(x+2\right)\left(x-3\right)=0\Leftrightarrow\left[{}\begin{matrix}x=-2\\x=3\end{matrix}\right.\)

a) \(\dfrac{9}{7}\div x=\dfrac{3}{5}\)

           \(x=\dfrac{9}{7}\div\dfrac{3}{5}\)

          \(x=\dfrac{15}{7}\)

b) \(x+\dfrac{1}{3}=\dfrac{8}{6}-\dfrac{1}{2}\)

    \(x+\dfrac{1}{3}=\dfrac{5}{6}\)

    \(x=\dfrac{5}{6}-\dfrac{1}{3}\)

   \(x=\dfrac{1}{2}\)

a) x = 3/5 x 9/7

x = 27/35

b) x+ 1/3 = 5/6

x = 5/6 - 1/3

x = 1/2

a)\(=>x=\dfrac{9}{7}:\dfrac{3}{5}=\dfrac{15}{7}\)

b)\(x=\left(\dfrac{8}{6}-\dfrac{1}{2}\right)-\dfrac{1}{3}=\dfrac{1}{2}\)

Bài 3a) 576 + 678 + 780 - 475 - 577 - 679

= ( 578 - 475 ) + ( 678 - 577 ) + ( 780 - 679 )

= 103 + 101 + 101

= 305

b) ( 126 + 32 ) x ( 18 - 16 - 2 ) 

= 158 x 0 

= 0 

c) 36 x 17 + 12 x 34 + 6 x 30 

= 6 x 6 x 17 + 6 x 2 x 34 + 6 x 30

= 6 x 102 + 6 x 68 + 6 x 30

= 6 x ( 102 + 68 + 30 )

= 6 x 200

= 1200

Bài 4:a. x × 6 = 3048 : 2

x × 6 = 1524

x = 1524 : 6

x = 254

b. 56 : x = 1326 – 1318

56 : x = 8

x = 56 : 8

x = 7

Bài 4: 

a) Ta có: \(x\cdot6=3048:2\)
nên 6x=1524

hay x=254

b) Ta có: 56:x=1326-1318

nên 56:x=8

hay x=7

b: =>3x+9=0 và y^2-9=0 và x+y=0

=>x=-3; y=3

a: (2x-5)(y+3)=-22

mà x,y là số nguyên

nên \(\left(2x-5;y+3\right)\in\left\{\left(1;-22\right);\left(11;-2\right);\left(-1;22\right);\left(-11;2\right)\right\}\)

=>\(\left(x,y\right)\in\left\{\left(3;-25\right);\left(8;-5\right);\left(2;19\right);\left(-3;-1\right)\right\}\)

a) x * 2 + x * 3 = 60

x * ( 2 + 3 ) = 60

x = 60 : 5

x = 12

b) x * 15 - x * 9 = 78

x * ( 15 - 9 ) = 78

x = 78 : 6

x = 13

Bài 4: 

a) \(\dfrac{4}{3}+\left(1,25-x\right)=2,25\)

\(1,25-x=2,25-\dfrac{4}{3}=\dfrac{9}{4}-\dfrac{4}{3}\)

\(1,25-x=\dfrac{11}{12}\)

\(x=1,25-\dfrac{11}{12}=\dfrac{5}{4}-\dfrac{11}{12}\)

\(x=\dfrac{1}{3}\)

b) \(\dfrac{17}{6}-\left(x-\dfrac{7}{6}\right)=\dfrac{7}{4}\)

\(x-\dfrac{7}{6}=\dfrac{17}{6}-\dfrac{7}{4}=\dfrac{34}{12}-\dfrac{21}{12}\)

\(x-\dfrac{7}{6}=\dfrac{13}{12}\)

\(x=\dfrac{13}{12}+\dfrac{7}{6}=\dfrac{13}{12}+\dfrac{14}{12}\)

\(x=\dfrac{27}{12}=\dfrac{9}{4}\)

c) \(4-\left(2x+1\right)=3-\dfrac{1}{3}=\dfrac{9}{3}-\dfrac{1}{3}\)

\(4-\left(2x+1\right)=\dfrac{8}{3}\)

\(2x+1=\dfrac{8}{3}+4=\dfrac{8}{3}+\dfrac{12}{3}\)

\(2x+1=\dfrac{20}{3}\)

\(2x=\dfrac{20}{3}-1=\dfrac{20}{3}-\dfrac{3}{3}\)

\(2x=\dfrac{17}{3}\)

\(x=\dfrac{17}{3}.\dfrac{1}{2}=\dfrac{17}{6}\)

Bài 15:

a) \(\left(\dfrac{-2}{3}\right)^9:x=\dfrac{-2}{3}\)

\(x=\left(\dfrac{-2}{3}\right)^9:\dfrac{-2}{3}=\left(\dfrac{-2}{3}\right)^{9-1}\)

\(=>x=\left(\dfrac{-2}{3}\right)^8\)

b) \(x:\left(\dfrac{4}{9}\right)^5=\left(\dfrac{4}{9}\right)^4\)

\(x=\left(\dfrac{4}{9}\right)^4.\left(\dfrac{4}{9}\right)^5=\left(\dfrac{4}{9}\right)^{4+5}\)

\(=>x=\left(\dfrac{4}{9}\right)^9\)

c) \(\left(x+4\right)^3=-125\)

\(\left(x+4\right)^3=\left(-5\right)^3\)

\(=>x+4=-5\)

\(x=-5-4\)

\(=>x=-9\)

d) \(\left(10-5x\right)^3=64\)

\(\left(10-5x\right)^3=4^3\)

\(=>10-5x=4\)

\(5x=10-4\)

\(5x=6\)

\(=>x=\dfrac{6}{5}\)

e) \(\left(4x+5\right)^2=81\)

\(\Leftrightarrow\left[{}\begin{matrix}\left(4x+5\right)^2=\left(-9\right)^2\\\left(4x+5\right)^2=9^2\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}4x+5=-9\\4x+5=9\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}4x=-14\\4x=4\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{-14}{4}\\x=1\end{matrix}\right.\)

Bài 16:

a) \(4-1\dfrac{2}{5}-\dfrac{8}{3}\)

\(=4-\dfrac{7}{5}-\dfrac{8}{3}\)

\(=\dfrac{60-21-40}{15}=\dfrac{-1}{15}\)

b) \(-0,6-\dfrac{-4}{9}-\dfrac{16}{15}\)

\(=\dfrac{-3}{5}+\dfrac{4}{9}-\dfrac{16}{15}\)

\(=\dfrac{\left(-27\right)+20-48}{45}=\dfrac{-55}{45}=\dfrac{-11}{9}\)

c) \(-\dfrac{15}{4}.\left(\dfrac{-7}{15}\right).\left(-2\dfrac{2}{5}\right)\)

\(=\dfrac{7}{4}.\dfrac{-12}{5}\)

\(=\dfrac{-21}{5}\)

\(#Wendy.Dang\)

Uh, chừa sau k dám học muộn nx

Đăng từng bài `1` thôi cậu ơii

a) \(\Leftrightarrow x^2-36=64\)

\(\Leftrightarrow x^2=100\)

\(\Leftrightarrow x=\pm10\)

Vậy \(x=\pm10\)

b) \(\Leftrightarrow x^2-x-3x+3=0\)

\(\Leftrightarrow x\left(x-1\right)-3\left(x-1\right)=0\)

\(\Leftrightarrow\left(x-1\right)\left(x-3\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x-1=0\\x-3=0\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}x=1\\x=3\end{matrix}\right.\)

Vậy \(x\in\left\{1;3\right\}\)