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a) x-45= -15+50
x-45= 35
x=35+45
x=80
b) 2x = -35+17
2x = -18
x = -9
c) -3 (x-4)=9-12
-3(x-4)= -3
x-4= 1
x=5
d) -36 - 4x +15 = 11
-36 - 4x = 11- 15
-36- 4x = -4
4x = -36 - (-4)
4x = -36+4 = -32
x = -32 : 4
x = -8
e) 125 - ( 3x - 20 ) = 115
3x - 20 = 125 - 115
3x -20 = 10
3x = 10+20= 30
x = 30: 3
x = 10
tick nhe ban oi
a/ (x-45) - 50 = -15
x - 45 = -15 + 50
x - 45 = 35
x = 35 + 45
x = 80
b/ 2x -17 = -35
2x = -35 + 17
2x = -18
x = -18 : 2
x = -9
\(a,2-x=17-\left(-5\right)\)
\(\Rightarrow2-x=17+5\)
\(\Rightarrow2-x=22\)
\(\Rightarrow x=2-22\)
\(\Rightarrow x=-20\)
Vay...
\(b,11-\left(15+11\right)=x-\left(25-9\right)\)
\(\Rightarrow11-26=x-16\)
\(\Rightarrow-15=x-16\)
\(\Rightarrow-15+16=x\)
\(\Rightarrow x=1\)
A , 3 - ( 17 - x ) = 289 - ( 36 + 289 )
3 - 17 + x = 0 - 36
-14 + x = -36
x = -36 - ( - 14 ) = -22
B, 25 - ( x + 5 ) = -415 - ( 15 - 415 )
25 - x - 5 = 0 - 15
20 - x = -15
x = 20 - ( - 15 ) = 35
C , 34 + ( 21 - x ) = ( 3747 - 30 ) - 3746
34 + 21 - x = 1 - 30
55 - x = -29
x = 55 - (-29 ) = 74
D , -2x - ( x -17 ) = 34 - ( -x + 25 )
- 2x - x + 17 = 34 - 25 + x
- 3x + 17 = 9 + x
- 3x - x = 9 - 17
-4x = -8
x = -8 : ( - 4 )
x = 2
E , 17x + ( -16x - 37 ) = x + 43
17x - 16x -37 = x + 43
x - 37 = x + 43
-37 - 43 = x - x
- 80 = 0 ( vô lý )
G , ( x + 12 ) . (x - 3 ) = 0
\(\hept{\begin{cases}x+12=0\\x-3=0\end{cases}}\)
\(\hept{\begin{cases}x=-12\\x=3\end{cases}}\)
1,-12 + x = 5x - 20
-12 + 20 = 5x - x
8 = 4x
x = 2
2, 7x - 4 = 20 + 3x
7x - 3x = 20 + 4
4x = 24
x = 6
3 , 5x - 7 = -21 - 2x
5x + 2x = -21 + 7
7x = -14
x = -14 : 7 = -2
4 , x + 15 = 20 - 4x
x + 4x = 20 - 15
5x = 5
x = 5 : 5 = 1
5, 17 - x = 7 - 6x
-x + 6x = 7 - 17
5x = -10
x = -10 : 5 = -2
b) 25 -2x =27
2x =27-25
2x= 2
x= 2:2
x=1
Vậy...
Câu 1 thiếu đề r bn
b, 25 - 2x = 27
=) 2x = 25 - 27 = -2
=) x = -2 : 2 = -1
c) 29 -x = -30
x= 29 -( -30)
x= 59
Vậy....
c, 29 -x = -30
=) x = 29 - ( - 30 ) = 29 + 30 = 59
=) x = 59
d) 4x - 45 = 17
4x =17+45
4x= 62
x= 62:4
x= 31/2
Vậy...
Đề sai sai
d, 4x - 45 = 17
=) 4x = 17 + 45 = 62
=) x = 62 : 4 = 13
e) 12 - ( 30 - x) = -23
30-x= 12-(-23)
30-x =35
x= 30 -35
x= -5
Vậy..
e, 12 - ( 30 - x) = -23
=) 30 - x = 12-(-23) 35
=) X = 30 - 35 = -5
f) | x - 7 | + 15 = 28
| x - 7 | = 28 -15
| x - 7 | =13
TH1; x-7 =13
x= 13+7
x= 20
TH2: x - 7 = -13
x= -13+7
x= -6
Vậy...
f, | x - 7 | + 15 = 28
=) | x - 7 | = 28 - 15 = 13
=) 2th
TH1 : x-7 = 13 =) x= 13 + 7 = 20
TH2 : x-7 = -13 =) x = -13 + 7 = -6
vậy x \(\in\){ -6 ; 20 }
Câu a sai đề
b) \(25-2x=27\Leftrightarrow2x=25-27=-2\Leftrightarrow x=\left(-2\right)\div2=-1\)
c) \(29-x=-30\Leftrightarrow x=29-\left(-30\right)=29+30=59\)
d) \(4x-45=17\Leftrightarrow4x=45+17=68\Leftrightarrow x=68\div4=17\)
e) \(12-\left(30-x\right)=-23\Leftrightarrow30-x=12-\left(-23\right)=12+23=35\)
\(\Leftrightarrow30-x=35\Leftrightarrow x=30-35\Leftrightarrow x=-5\)
f) \(|x-7|+15=28\Leftrightarrow|x-7|=28-15=13\) . Xét 2 trường hợp :
\(x-7=13\Rightarrow x=13+7=20\) ; \(x-7=-13\Rightarrow x=\left(-13\right)+7=-6\)