\(a,\Leftrightarrow x-1=4\Leftrightarrow x=5\\ b,\Leftrightarrow\left\{{}\begin{matrix}x\ge\dfrac{3}{4}\\3x+1=4x-3\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x\ge\dfrac{3}{4}\\x=4\left(tm\right)\end{matrix}\right.\Leftrightarrow x=4\\ c,ĐK:x\ge-5\\ PT\Leftrightarrow2\sqrt{x+5}-3\sqrt{x+5}+4\sqrt{x+5}=6\\ \Leftrightarrow3\sqrt{x+5}=6\\ \Leftrightarrow\sqrt{x+5}=3\\ \Leftrightarrow x+5=9\\ \Leftrightarrow x=4\left(tm\right)\)

\(d,\Leftrightarrow\sqrt{\left(x-2\right)^2}=\sqrt{\left(\sqrt{5}+1\right)^2}\\ \Leftrightarrow\left|x-2\right|=\sqrt{5}+1\\ \Leftrightarrow\left[{}\begin{matrix}x-2=\sqrt{5}+1\\2-x=\sqrt{5}+1\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\sqrt{5}+3\\x=1-\sqrt{5}\end{matrix}\right.\)

tra loi xong cho minh dung nhe

8x8

ko bít làm

ko biet

a) x+15=20-4x

    x+4x=20-15

        5x=5

          x=5:5

          x=1

Vậy x=1

b) 8x+|-3|=-4x+39

    8x+4x=39-3

    12x=36

        x=36:12

        x=3

Vậy x=3

c) 6(x-2)+(-2)=20-4x

    6x-12-2=20-4x

    6x+4x=20+12+2

    10x=34

        x=34:10

        x=3,4

Vậy x=3,4

a) x+15=20-4x

<=> x+15-20+4x=0

<=> 5x+5=0

<=> 5x=-5

<=>x=-1

Vậy x=-1

b) 8x+|-3|=-4x+39

<=> 8x+3=-4x+39

<=> 8x+3+4x-39=0

<=> 12x-30=0

<=>12x=30

<=>x=5/2

Vậy x=5/2

c) 6(x-2)+(-2)=20-4x

<=> 6x-12-2=20-4x

<=> 6x-14=20-4x

<=> 6x-14-20+4x=0

<=> 10x-34=0

<=>10x=34

<=>x=17/5

Vậy x=17/5

a) x+15=20-4x

   x + 4x = 20 - 15

     5x      = 5

         x    = 5 : 5

         x     = 1

b) 8x+|-3|=-4x+39

   8x + 3   = -4  + 39

    8x + 3  = 35

    8x        = 35 - 3

       8x     = 32

       x       = 32 : 8

       x       = 4

c) 6(x-2)+(-2)=20-4x

    6x - 12 + (-2) = 20 - 4x

     6x + 4x         = 20 + 12 + 2

       10x              = 34

        x                 = 34 : 10

          x               = 3,4

# HOK TỐT #

Ta có : 5x + 20 - x² - 4x = 0 

=> 5(x + 4) - (x² + 4x) = 0

=> 5(x + 4) - x(x + 4) = 0

=> (x + 4) ( 5 - x) = 0

\(\Rightarrow\orbr{\begin{cases}x+4=0\\x-5=0\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=-4\\x=5\end{cases}}\)

b) tương tự nhá 

a)   5x + 20 - x² -4x =0

<=> (5x+20)- (x²+4x)=0

<=>5(x+4)-x(x+4)=0

<=>(5-x)(x+4)=0 

<=> 5-x=0 hoặc x+4=0 

<=> x=5 hoặc x=-4

b) x²+3x -(2x+6)=0

<=>(x²+3x)-2(x+3)=0

<=>x(x+3)-2(x+3)=0

<=>(x-2)(x+3)=0

<=> x-2=0 hoặc x+3=0 

<=>x=2 hoặc x=-3

\(a.5x+20-x^2-4x=0\)

\(\Leftrightarrow5\left(x+4\right)-x\left(x+4\right)=0\)

\(\Leftrightarrow\left(5-x\right)\left(x+4\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}5-x=0\\x+4=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=5\\x=-4\end{cases}}\)

\(b.x^2+3x-\left(2x+6\right)=0\)

\(\Leftrightarrow x^2+3x-2x-6=0\)

\(\Leftrightarrow x\left(x+3\right)-2\left(x+3\right)=0\)

\(\Leftrightarrow\left(x-2\right)\left(x+3\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x-2=0\\x+3=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=2\\x=-3\end{cases}}\)

Câu 6: Khôg có cau nào đúng

Câu 7: C

Câu 8: B

Câu 9: B

Câu 10: D

6Không có đáp án nào đúng x=11/4

7C

8B

9B

10D

5.

$4x+3\vdots x-2$

$\Rightarrow 4(x-2)+11\vdots x-2$

$\Rightarrow 11\vdots x-2$

$\Rightarrow x-2\in \left\{1; -1; 11; -11\right\}$

$\Rightarrow x\in \left\{3; 1; 13; -9\right\}$

6.

$3x+9\vdots x+2$
$\Rightarrow 3(x+2)+3\vdots x+2$
$\Rightarrow 3\vdots x+2$

$\Rightarrow x+2\in \left\{1; -1; 3; -3\right\}$

$\Rightarrow x\in \left\{-1; -3; 1; -5\right\}$

7.

$3x+16\vdots x+1$

$\Rightarrow 3(x+1)+13\vdots x+1$

$\Rightarrow 13\vdots x+1$

$\Rightarrow x+1\in \left\{1; -1; 13; -13\right\}$

$\Rightarrow x\in\left\{0; -2; 12; -14\right\}$

8.

$4x+69\vdots x+5$

$\Rightarrow 4(x+5)+49\vdots x+5$

$\Rightarrow 49\vdots x+5$

$\Rightarrow x+5\in\left\{1; -1; 7; -7; 49; -49\right\}$

$\Rightarrow x\in \left\{-4; -6; 2; -12; 44; -54\right\}$

** Bổ sung điều kiện $x$ là số nguyên.

1. $x+9\vdots x+7$

$\Rightarrow (x+7)+2\vdots x+7$

$\Rightarrow 2\vdots x+7$

$\Rightarrow x+7\in \left\{1; -1; 2; -2\right\}$

$\Rightarrow x\in \left\{-6; -8; -5; -9\right\}$

2. Làm tương tự câu 1

$\Rightarrow 9\vdots x+1$

3. Làm tương tự câu 1

$\Rightarrow 17\vdots x+2$
4. Làm tương tự câu 1

$\Rightarrow 18\vdots x+2$