a) `4x(x-5)-(x-1)(x-3)=23`

`<=> 4x^2-20x-x^2+4x-3=23`

`<=>3x^2-16x-26=0`

`<=> x=(8+-\sqrt142)/3

*Nếu đề là: `4x(x-5)-(x-1)(4x-3)=23`

`<=> 4x^2-20x-4x^2+7x-3=23`

`<=>-13x=26`

`<=>x=-2`

b) `(x-5)(x-4)-(x+1)(x-2)=7`

`<=>x^2-9x+20-x^2+x+2=7`

`<=>-8x=-15`

`<=>x=15/8`

\(\text{a) 4x(x-5)-(x-1)(1x-3)=23}\)

\(\Leftrightarrow4x^2-20x-\left(x^2-3x-x+3\right)=23\)

\(\Leftrightarrow4x^2-20x-x^2+3x+x-3=23\)

\(\Leftrightarrow3x^2-16x-26=0\)

Giải phương trình bậc 2 một ẩn ta được :

\(x_1=\dfrac{8-\sqrt{142}}{3};x_2=\dfrac{8+\sqrt{142}}{3}\)

\(a,\Leftrightarrow4x^2-20x-4x^2+7x-3=23\\ \Leftrightarrow-13x=-26\\ \Leftrightarrow x=2\\ b,\Leftrightarrow x^2+4x+4+4x^2-12x+9=5x^2+35x\\ \Leftrightarrow-43x=-13\\ \Leftrightarrow x=\dfrac{13}{43}\)

a) \(4x\left(x-5\right)-\left(x-1\right)\left(4x-3\right)=23\)

\(\Leftrightarrow4x^2-20x-4x^2+7x-3=23\)

\(\Leftrightarrow13x=-26\Leftrightarrow x=-2\)

b) \(\left(x+2\right)^2+\left(2x-3\right)^2=5x\left(x+7\right)\)

\(\Leftrightarrow x^2+4x+4+4x^2-12x+9=5x^2+35x\)

\(\Leftrightarrow43x=13\Leftrightarrow x=\dfrac{13}{43}\)

3+5/x-1

3+36/x-4

x+1+4/x+1

x+1/x-5

a: 3x+2 chia hết cho x-1

=>3x-3+5 chia hết cho x-1

=>5 chia hết cho x-1

=>x-1 thuộc {1;-1;5;-5}

=>x thuộc {2;0;6;-4}

b: 3x+24 chia hết cho x-4

=>3x-12+36 chia hết cho x-4

=>36 chia hết cho x-4

=>x-4 thuộc {1;-1;2;-2;3;-3;4;-4;6;-6;9;-9;12;-12;18;-18;36;-36}

=>x thuộc {5;3;6;2;7;1;8;0;10;-2;13;-5;16;-8;22;-14;40;-32}

c: x^2+5 chia hết cho x+1

=>x^2-1+6 chia hết cho x+1

=>x+1 thuộc {1;-1;2;-2;3;-3;6;-6}

=>x thuộc {0;-2;1;-3;2;-4;5;-7}

d: x^2-5x+1 chia hết cho x-5

=>1 chia hết cho x-5

=>x-5 thuộc {1;-1}

=>x thuộc {6;4}

mọi người giúp với 

a: Bạn ghi lại đề nha bạn

b: \(30\left(x+2\right)-6\left(x-5\right)-24x=100\)

=>\(30x+60-6x+30-24x=100\)

=>\(\left(30x-6x-24x\right)+\left(60+30\right)=100\)

=>0x=100-90=10(vô lý)

c: \(\left(x-7\right)\left(x+3\right)< 0\)

TH1: \(\left\{{}\begin{matrix}x-7>0\\x+3< 0\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}x>7\\x< -3\end{matrix}\right.\)

=>\(x\in\varnothing\)

TH2: \(\left\{{}\begin{matrix}x-7< 0\\x+3>0\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}x< 7\\x>-3\end{matrix}\right.\)

=>-3<x<7

mà x nguyên

nên \(x\in\left\{-2;-1;0;1;2;3;4;5;6\right\}\)

d: -1<2x-1<4

=>\(-1+1< 2x< 4+1\)

=>0<2x<5

=>0<x<2,5

mà x nguyên

nên \(x\in\left\{1;2\right\}\)

a: x(x+5)=0

=>\(\left[{}\begin{matrix}x=0\\x+5=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-5\end{matrix}\right.\)

b: 2x(x+3)=0

=>x(x+3)=0

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

c: \(\left(6-x\right)\left(x+10\right)=0\)

=>\(\left[{}\begin{matrix}6-x=0\\x+10=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=6-0=6\\x=0-10=-10\end{matrix}\right.\)

d: \(\left(5x+20\right)\left(x^2+1\right)=0\)

=>\(5x+20=0\left(x^2+1>=1>0\forall x\right)\)

=>5x=-20

=>x=-4

1)

\(x-17=23\\ \Rightarrow x=23+17\\ \Rightarrow x=40\)

2)

\(2\left(x-1\right)=7+\left(-3\right)\\ \Rightarrow2x-2=4\\ \Rightarrow2x=4+2\\ \Rightarrow2x=8\\ \Rightarrow x=4\)

3)

\(4\left(x+5\right)^3-7=101\\ \Rightarrow4\left(x+5\right)^3=101+7\\ \Rightarrow4\left(x+5\right)^3=108\\ \Rightarrow\left(x+5\right)^3=108\div4\\ \Rightarrow\left(x+5\right)^3=27\\ \Rightarrow\left(x+5\right)^3=3^3\\ \Rightarrow x+5=3\Rightarrow x=3-5\\ \Rightarrow x=-2\)

4)

\(2^{x+1}\times3+15=39\\ \Rightarrow2^{x+1}\times3=39-15\\ \Rightarrow2^{x+1}\times3=24\\ \Rightarrow2^{x+1}=24\div3\\ \Rightarrow2^{x+1}=8\)

\( \Rightarrow2^{2+1}=8\\\Rightarrow2^3=8\Rightarrow x=2 \)

a) x - 17 = 23

x = 23 + 17

x = 40

Vậy x = 40

b) 2 ( x - 1 ) = 7 + ( - 3 )

x - 1 = 4 : 2

x = 2 + 1

x = 3

Vậy x = 3

c) 4 ( x + 3 )^3 - 7 = 101

4 ( x + 3 )^3 = ( 101 + 7 ) : 4

( x + 3 )^3 = 3^3

⇒ x + 3 = 3

⇒ x = 0

Vậy x = 0

d) 2^{ x+ 1 } . 3 + 15 = 39

2^{ x + 1 } = ( 39 - 15 ) : 3

2^{ x + 1 } = 2{ 2 + 1 }

⇒ x + 1 = 2 + 1

⇒ x = 2

Vậy x = 2

câu 1:

a) 500-(300)-190+(-210)

= 500-300-190-210

= 200 - 210 -190

=-10 - 190

=-200

b) (-3)³ .5+12.(-6)

= -27.5 -72

=-135 - 72

=-207

c) 15.(-19-4)-19.(15-4)

= 15.(-23) - 19.11

=-345 - 209

=-554

câu 2: tìm x thuộc Z

a) 3x-2=3

=> 3x=3/2

=> x=1/2

b) x chia hết cho 5 và -7<x<11

=> x thuộc {-5;0;5;10}

Câu 1: 

a) Ta có: \(500-\left(300\right)-190+\left(-210\right)\)

\(=500-300-190-210\)

\(=\left(500-300\right)-\left(190+210\right)\)

\(=200-400=-200\)

b) Ta có: \(\left(-3\right)^3\cdot5+12\cdot\left(-6\right)\)

\(=\left(-3\right)^3\cdot5-3\cdot4\cdot3\cdot2\)

\(=-5\cdot3^3-3^2\cdot8\)

\(=3^2\cdot\left(-5\cdot3-8\right)\)

\(=9\cdot\left(-15-8\right)=9\cdot\left(-23\right)=-207\)

c) Ta có: \(15\cdot\left(-19-4\right)-19\cdot\left(15-4\right)\)

\(=-15\cdot19-15\cdot4-15\cdot19+19\cdot4\)

\(=-30\cdot19+4\cdot4\)

\(=-2\cdot\left(15\cdot19+2\cdot4\right)\)

\(=-2\cdot\left(285+8\right)=-586\)

a: =>5-x=-23

=>x=5+23=28

b: =>x-3-x+7-25+x=54

=>x-21=54

=>x=75

c: =>7-9x-2x+4=-5x-35+27-25=-5x-37

=>-11x+3=-5x-37

=>-6x=-40

=>x=20/3

a) \(10-x-5=\left(-5\right)-7-11\)

\(\Rightarrow5-x=-23\)

\(\Rightarrow x=5+23\)

\(\Rightarrow x=28\)

b) \(\left(x-3\right)-\left(x+17-24\right)-\left(25-x\right)=24-\left(-30\right)\)

\(\Rightarrow x-3-x-17+24-25+x=54\)

\(\Rightarrow x-21=54\)

\(\Rightarrow x=54+21\)

\(\Rightarrow x=75\)

c) \(\left(7-9x\right)-\left(2x-4\right)=-\left(5x+35\right)-\left(-27\right)-25\)

\(\Rightarrow7-9x-2x+4=-5x-35+27-25\)

\(\Rightarrow11-11x=-5x-33\)

\(\Rightarrow-11x+5x=-33-11\)

\(\Rightarrow-6x=-22\)

\(\Rightarrow x=\dfrac{22}{6}=\dfrac{11}{3}\)

a. 
10-x-5 = (-5) - 7 -11
=>5-x = 0
=>x=5
b
(x-3) - (x+17-24) - (25-x) = 24 - (-30)
=>x - 3 - x - 17 + 24 - 25 - x = 24 + 30
=>-x - 21 = 54
=>-x = 75
=>x = -75
c
(7 - 9x) - (2x - 4) = - (5x + 35) - (-27) - 25
=>7-9x - 2x + 4 = -5x - 35 + 27 - 35
=>11 - 11x + 5x = -43
=>16x = 11 + 43
=>16x = 54
=>x=4