a: \(\Leftrightarrow x^2+10x+25-x^2+4x=55\)

=>14x=30

hay x=15/7

b: \(\Leftrightarrow\left(x-7\right)\left(x-3\right)=0\)

hay \(x\in\left\{7;3\right\}\)

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`

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

c) Ta có: \(\left|x-\dfrac{2}{3}\right|+2.25=\dfrac{3}{4}\)

\(\Leftrightarrow\left|x-\dfrac{2}{3}\right|=\dfrac{3}{4}-\dfrac{9}{4}=\dfrac{-3}{2}\)(vô lý)

Vậy: \(x\in\varnothing\)

a) Ta có: \(x+\dfrac{-3}{7}=\dfrac{4}{7}\)

\(\Leftrightarrow x-\dfrac{3}{7}=\dfrac{4}{7}\)

hay x=1

Vậy: x=1

b) Ta có: \(\dfrac{1}{2}x-75\%=\dfrac{1}{4}\)

\(\Leftrightarrow x\cdot\dfrac{1}{2}=1\)

hay x=2

Vậy: x=2

\(a.\)

\(\left(x-19\right)\left(x+21\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x-19=0\\x+21=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=19\\x=-21\end{matrix}\right.\)

\(S=\left\{19,-21\right\}\)

\(b.\)

\(\left(53-x\right)\left(41+x\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}53-x=0\\41+x=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=53\\x=-41\end{matrix}\right.\)

\(S=\left\{53,-41\right\}\)

Tìm x:

a) (x-19).(x+21)=0

<=>\(\left\{{}\begin{matrix}x-19=0< =>x=19\\x+21=0< =>x=-21\end{matrix}\right.\)

Vậy pt trên có tập nghiệm là: S={19;-21}

b)(53-x).(41+x)=0

<=>\(\left\{{}\begin{matrix}53-x=0< =>x=53\\41+x=0< =>x=-41\end{matrix}\right.\)

Vậy pt trên có tập nghiệm là S={53;-41}

a) x là 19 hoặc -21

b) x là 53 hoặc-41

cho tớ tim nhá

a) Ta có: \(\left|4-5x\right|=24\)

\(\Leftrightarrow\left[{}\begin{matrix}-5x+4=24\\-5x+4=-24\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}-5x=20\\-5x=-28\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-4\\x=\dfrac{28}{5}\end{matrix}\right.\)

Vậy: \(x\in\left\{-4;\dfrac{28}{5}\right\}\)

b) Ta có: \(\left(8+x\right)\left(6-x\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x+8=0\\6-x=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-8\\x=6\end{matrix}\right.\)

Vậy: \(x\in\left\{-8;6\right\}\)

a) \(\left|4-5x\right|=24\)

\(\Leftrightarrow\left[{}\begin{matrix}4-5x=24\\4-5x=-24\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-4\\x=\dfrac{28}{5}\end{matrix}\right.\)

b) \(\left(8+x\right)\left(6-x\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}8+x=0\\6-x=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-8\\x=6\end{matrix}\right.\)

a.|4-5.x|=24

TH1: 4-5.x=24

        ⇔5x=-20

        ⇔x=-4

TH1: 4-5.x=-24

        ⇔5x=28

        ⇔x=28/5

b.(8+x).(6-x)=0

\(\left\{{}\begin{matrix}8+x=0\\6-x=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=-8\\x=6\end{matrix}\right.\)

a: =>x*21=3885:37=105

=>x=105:21=5

b: 50343:x=405 dư 123

=>x=(50343-123)/405=124

a, 3885 : (X x 21) = 37
=> 21X = 3885/37
=> 21X = 105
=> X = 5
b, 50343 : X = 405 (dư 123)
=> X = 50343 : 405 + 123
=> X = 33386/135

a) \(3885:\left(x\times21\right)=37\)

\(x\times21=3885:37\)

\(x\times21=105\)

\(x=105:21=5\)

b) \(50343:x=405\)(dư 123)

=> \(405\times x+123=50343\)

\(405\times x=50343-123\)

\(405\times x=50220\)

\(x=50220:405=124\)