a: =>|x-3|=4

\(\Leftrightarrow\left[{}\begin{matrix}x-3=4\\x-3=-4\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=7\\x=-1\end{matrix}\right.\)

b: =>|x+2|=15

\(\Leftrightarrow\left[{}\begin{matrix}x+2=15\\x+2=-15\end{matrix}\right.\Leftrightarrow x\in\left\{13;-17\right\}\)

`@` `\text {Ans}`

`\downarrow`

`c)`

`( 34 - 2x ) . ( 2x - 6 ) = 0`

`=>`\(\left[{}\begin{matrix}34-2x=0\\2x-6=0\end{matrix}\right.\)

`=>`\(\left[{}\begin{matrix}2x=34\\2x=6\end{matrix}\right.\)

`=>`\(\left[{}\begin{matrix}x=34\div2\\x=6\div2\end{matrix}\right.\)

`=>`\(\left[{}\begin{matrix}x=17\\x=3\end{matrix}\right.\)

Vậy, `x \in {17; 3}`

`d)`

`( 2019 - x ) . ( 3x - 12 ) =0` `?`

`=>`\(\left[{}\begin{matrix}2019-x=0\\3x-12=0\end{matrix}\right.\)

`=>`\(\left[{}\begin{matrix}x=2019-0\\3x=12\end{matrix}\right.\)

`=>`\(\left[{}\begin{matrix}x=2019\\x=12\div3\end{matrix}\right.\)

`=>`\(\left[{}\begin{matrix}x=2019\\x=4\end{matrix}\right.\)

Vậy, `x \in {2019; 4}`

`e) `

`57 . ( 9x - 27 ) = 0`

`=>`\(9x-27=0\div57\)

`=> 9x - 27 = 0`

`=> 9x = 27`

`=> x = 27 \div 9`

`=> x = 3`

Vậy, `x = 3`

`f)`

`25 + ( 15 - x ) = 30`

`=> 15 - x = 30 - 25`

`=> 15 - x = 5`

`=> x = 15 -5 `

`=> x = 10`

Vậy, `x = 10`

`g) `

`43 - ( 24 - x ) = 20`

`=> 24 - x = 43 - 20`

`=> 24 - x = 23`

`=> x = 24 - 23`

`=> x = 1`

Vậy, `x = 1`

`h) `

`2 . ( x - 5 ) - 17 = 25`

`=> 2 ( x - 5) = 25+17`

`=> 2 ( x - 5) = 42`

`=> x - 5 = 42 \div 2`

`=> x - 5 = 21`

`=> x = 21 + 5`

`=> x = 26`

Vậy, `x = 26`

`i)`

`3 . ( x + 7 ) - 15 = 27`

`=> 3(x + 7) = 27 + 15`

`=> 3(x + 7) = 42`

`=> x +7 = 42 \div 3`

`=> x + 7 = 14`

`=> x = 14 - 7`

`=> x = 7`

Vậy, `x = 7`

`j)`

`15 + 4 . ( x - 2 ) = 95`

`=> 4(x - 2) = 95 - 15`

`=> 4(x - 2) = 80`

`=> x - 2 = 80 \div 4`

`=> x - 2 = 20`

`=> x = 20 + 2`

`=> x = 22`

Vậy, `x = 22`

`k)`

`20 - ( x + 14 ) = 5`

`=> x + 14 = 20 - 5`

`=> x + 14 = 15`

`=> x = 15 - 14`

`=> x = 1`

Vậy, `x = 1`

`l) `

`14 + 3 . ( 5 - x ) = 27`

`=> 3(5 - x) = 27 - 14`

`=> 3(5 - x) = 13`

`=> 5 - x = 13 \div 3`

`=> 5 - x = 13/3`

`=> x = 5- 13/3`

`=> x = 2/3`

Vậy, `x = 2/3.`

`@` `\text {Kaizuu lv uuu}`

nhanh mik tick cho nha

Đặt `B = |x - 1| + |x - 2| + |x - 3| + |x - 4|`

`= (|x - 1| + |x - 4|) + (|x - 2| + |x - 3|)`

`= (|x - 1| + |4 - x|) + (|x - 2| + |3 - x|)`

\(\Rightarrow B\ge\left|x-1+4-x\right|+\left|x-2+3-x\right|\)

\(B\ge\left|3\right|+\left|1\right|=4\)

\(\Rightarrow A\ge4+15=19\)

hay MinA = 19

Dấu "=" xảy ra khi: \(\left\{{}\begin{matrix}\left(x-1\right)\left(4-x\right)\ge0\\\left(x-2\right)\left(3-x\right)\ge0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}\left(x-1\right)\left(x-4\right)\le0\\\left(x-2\right)\left(x-3\right)\le0\end{matrix}\right.\)\(\Rightarrow\left\{{}\begin{matrix}1\le x\le4\\2\le x\le3\end{matrix}\right.\Rightarrow2\le x\le3\)

Vậy MinA = 19 tại \(2\le x\le3\).

k) 3 - ( 17 - x ) = 289 - ( 36 + 289 )

3 - 17 + x = 289 - 36 - 289

x = 289 - 36 - 289 - 3 + 17

x = -22

n) 25 - ( x + 15 ) = ( -415 ) - ( 15 - 415 )

25 - x - 15 = -415 - 15 + 415

25 - x - 15 = -15

25 - 15 + 15 = -x

-x = 25

=> x = -25

m) 34 + ( 21 - x ) = ( 3747 - 30 ) - 3747

34 + 21 - x = 3747 - 30 - 3747

34 + 21 - x = -30

34 + 21 + 30 = -x

-x = 85

=> x = -85

r) Hình như thiếu đề thì phải

HỌC TỐT !

trả lời :

mấy câu kia bạn tham khảo bạn I love You nha

còn câu r) thiếu đề x+2+15:|-3|=? ( chưa có kết quả)

học tốt

1)

25+27+x=21+l-22l

=>25+27+x=21+22

=>25+27+x=43

=>52+x=43

=>x=43-52

=>x=-9

2)

l-5l+l-7l=x+3

=>5+7=x+3

=>12=x+3

=>x=12-3

=>x=9

3)

8+lxl=l-8l+15

=>8+lxl=8+15

=>8+lxl=23

=>lxl=23-8

=>lxl=15

=>x=15 hoặc x=-15

4)

lxl+15=-7

=>lxl=-7-15

=>lxl=-22

=>x ko tồn tại

1)25+27+x=21+22                                      3)8+x=8+15

52+x=43                                                     8+x=23

x=52-43=9                                                 x=23-8=15

2)5+7=x+3                                                 x=15 hoặc x=-15

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

x=12-3=9                                                     x=(-7)-15=-22

                                                                   x=22 hoặc x=-22

1. -9

2. 9

3.15

4.ko có

a)|x+4/15|-3,75=-2,15

|x+4/15|=-2,15+3/75

|x+4/15|=1,6

=>x+4/15=1,6 hoặc x+4/15=-1,6

x=1,6-4/15              x=-1,6-4/15

x=4/3                      x=-28/15

b)|x-5/3|<1/3

*)x-5/3<1/3

x<1/3+5/3=6/3

x<2

*)x-5/3<-1/3

x<-1/3+5/3

x<4/3

=>x<4/3

Vậy x<4/3

x= -24 

nha bạn. đúng 100%. chọn mình nha

456465

\(9-\left(27-x\right)=\left|-27\right|-15\)

\(9-\left(27-x\right)=12\)

\(27-x=9-12\)

\(27-x=-3\)

\(x=27-\left(-3\right)\)

\(x=30\)