\(\Leftrightarrow5x+5=4x+12\)

hay x=7

nhiều quá :((

\(a,2\left(x-5\right)-3\left(x+7\right)=14\)

\(2x-10-3x-21=14\)

\(-x-31=14\)

\(-x=45\)

\(x=45\)

\(b,5\left(x-6\right)-2\left(x+3\right)=12\)

\(5x-30-2x-6=12\)

\(3x-36==12\)

\(3x=48\)

\(x=16\)

\(c,3\left(x-4\right)-\left(8-x\right)=12\)

\(3x-12-8+x=0\)

\(4x-20=0\)

\(4x=20\)

\(x=5\)

Cố nốt nha bn ! 

cảm ơn, bn nha:)))

mà hình như bạn TOP 3 trả lời câu hỏi pải ko nhỉ???

Lời giải:

1. $(x+2)-2=0$

$x+2=2$

$x=0$

2.

$(x+3)+1=7$

$x+3=7-1=6$

$x=6-3=3$

3.

$(3x-4)+4=12$

$3x-4+4=12$

$3x=12$

$x=12:3=4$

4.

$(5x+4)-1=13$

$5x+4=13+1=14$

$5x=14-4=10$

$x=10:5=2$

5.

$(4x-8)-3=5$

$4x-8=5+3=8$

$4x=8+8=16$

$x=16:4=4$

6.

$3+(x-5)=7$

$x-5=7-3=4$

$x=4+5=9$

7.

$8-(2x-4)=2$

$2x-4=8-2=6$

$2x=6+4=10$

$x=10:2=5$

8.

$7+(5x+2)=14$

$5x+2=14-7=7$

$5x=7-2=5$

$x=5:5=1$

9.

$5-(3x-11)=1$

$3x-11=5-1=4$

$3x=11+4=15$

$x=15:3=5$

10.

$16-(8x+2)=6$

$8x+2=16-6=10$

$8x=10-2=8$

$x=8:8=1$

1) |x + 2| = 4

\(\Leftrightarrow\orbr{\begin{cases}x+2=4\\x+2=-4\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=2\\x=-6\end{cases}}\)

2) 3 – |2x + 1| = (-5)

\(\Leftrightarrow\left|2x+1\right|=8\Leftrightarrow\orbr{\begin{cases}2x+1=8\\2x+1=-8\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=\frac{7}{2}\\x=\frac{-9}{2}\end{cases}}\)

3) 12 + |3 – x| = 9

\(\Leftrightarrow\left|3-x\right|=-3\)(vô lí)

=>\(x=\varnothing\) 

1) I x+2 I=4

\(\Rightarrow\orbr{\begin{cases}x+2=4\\x+2=-4\end{cases}\Leftrightarrow\orbr{\begin{cases}x=2\\x=-6\end{cases}}}\)

2) \(3-|2x+1|=-5\)

\(\Leftrightarrow|2x+1|=8\)

\(\Leftrightarrow\orbr{\begin{cases}2x+1=8\\2x+1=-8\end{cases}\Leftrightarrow\orbr{\begin{cases}2x=7\\2x=-9\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=\frac{7}{2}\\x=\frac{-9}{2}\end{cases}}}\)

3) \(12+|3-x|=9\)

\(\Leftrightarrow|3-x|=-3\)(vô lí vì I 3-x I \(\ge\)0)

Bài 1 :                                         Bài giải

\(-2\left(-3-4x\right)-3\left(3x-7\right)=31\)

\(6+8x-9x-21=31\)

\(-x-15=31\)

\(-x=31+15\)

\(-x=46\)

\(x=-46\)

b, \(10\left(x-7\right)=8\left(x-4\right)+x\)

\(10x-70=8x-32+x\)

\(10x-70=9x-32\)

\(10x-9x=-32+70\)

\(x=38\)

c, \(2\left|x-1\right|=3\cdot\left(5-1\right)\)

\(2\left|x-1\right|=15-3\)

\(2\left|x-1\right|=12\)
\(\left|x-1\right|=12\text{ : }2\)

\(\left|x-1\right|=6\)

\(\Rightarrow\orbr{\begin{cases}x-1=-6\\x-1=6\end{cases}}\Rightarrow\orbr{\begin{cases}x=-5\\x=7\end{cases}}\)

\(\Rightarrow\text{ }x\in\left\{-5\text{ ; }7\right\}\)

d, \(2\left(x+3\right)-2\left(x-3\right)=x\)

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

\(2\cdot0=x\)

\(x=0\)

e, \(\left(x+3\right)\left(x-4\right)=0\)

\(\Rightarrow\orbr{\begin{cases}x+3=0\\x-4=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=-3\\x=4\end{cases}}\)

\(\Rightarrow\text{ }x\in\left\{-3\text{ ; }4\right\}\)

a, \(-2\left(-3-4x\right)-3\left(3x-7\right)=31\)

\(6+8x-9x-21=31\)

\(-x-15=31\)

\(-x=31+15\)

\(-x=46\)

\(x=-46\)

b, \(10\left(x-7\right)=8\left(x-4\right)+x\)

\(10x-70=8x-32+x\)

\(10x-70=9x-32\)

\(10x-9x=-32+70\)

\(x=38\)

c, \(2\left|x-1\right|=3\cdot\left(5-1\right)\)

\(2\left|x-1\right|=15-3\)

\(2\left|x-1\right|=12\)
\(\left|x-1\right|=12\text{ : }2\)

\(\left|x-1\right|=6\)

\(\Rightarrow\orbr{\begin{cases}x-1=-6\\x-1=6\end{cases}}\Rightarrow\orbr{\begin{cases}x=-5\\x=7\end{cases}}\)

\(\Rightarrow\text{ }x\in\left\{-5\text{ ; }7\right\}\)

d, \(2\left(x+3\right)-2\left(x-3\right)=x\)

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

\(2\cdot0=x\)

\(x=0\)

e, \(\left(x+3\right)\left(x-4\right)=0\)

\(\Rightarrow\orbr{\begin{cases}x+3=0\\x-4=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=-3\\x=4\end{cases}}\)

\(\Rightarrow\text{ }x\in\left\{-3\text{ ; }4\right\}\)

1) <=> 8x-16-21-7x=-4

<=> x-37=-4

<=> x=33

2) <=> 12x-48+6x-12-16x-48=-28

<=> 2x-108=-28

<=> 2x = 80

<=> x = 40

3)<=> 4x-20-35+7x+50-10x=-3

<=> x-5=-3

<=> x=2

4) <=> -3x-15=-45-21

<=> 51=3x

<=> 17=x

5) 4x-28+15=-2x+14-10

<=> 6x-13=4

<=> 6x=17

<=> x = \(\frac{17}{6}\)

Chúc bạn học tốt

GIUP MINH BAI NAY DUOC KO

\(a)5\left(3-2x\right)+5\left(x-4\right)=6-4x\)

\(\Leftrightarrow5\left(3-2x+x-4\right)=6-4x\)

\(\Leftrightarrow5\left(-x-1\right)=6-4x\)

\(\Leftrightarrow-5x-5=6-4x\)

\(\Leftrightarrow-x=11\Leftrightarrow x=-11\)

Vậy \(x=-11\)

may bai nay de ma

sao ban khong tu lam di

thì bạn làm đi

-5(3x-7) - ( -15x+3) - ( 12 -x ) =-4

=>-15x+35+15x-3-12+x=-4

=>20+x=-4

=>x=-4-20

=>x=-24

-3(4x-2) - ( -12+8) - (-x)=0

=>-12x+6+12-8+x=0

=>-11x+10=0

=>-11x=0-10

=>-11x=-10

=>11x=10

=>x=10:11=\(\frac{10}{11}\)