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a)13-2(x+1)=7
2.(x+1)=13-7
2.(x+1)=6
x+1=6/2
x+1=3
x=3-1
x=2
a, 13 - 2 ( x + 1 ) = 7
2 .( x + 1 ) = 13 - 7
2 .( x + 1 ) = 6
x + 1 = 6 : 2
x + 1 = 3
x = 3 - 1
x = 4
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a) 210 -5.x= 200
<=> 5.x = 210 - 200
<=> 5.x = 10
<=> x = 10 : 5
<=> x = 2
Vậy x = 2
b) 210 - 5 . ( x-10 ) = 200
<=> 5. (x-10) = 210 - 200
<=> 5.(x-10) = 10
<=> x -10 = 10 : 5
<=> x - 10 = 2
<=>x = 12
Vậy x = 12
d)350 : x + 10 = 20
<=> 350 : x = 20 - 10
<=> 350 : x = 10
<=> x = 350 : 10
<=> x = 35
Vậy x = 35
e)36 : ( x - 5 ) = 22
<=> 36 : ( x-5) = 4
<=> x - 5 = 36 : 4
<=> x - 5 = 9
<=> x = 9 + 5
<=> x = 14
Vậy x =14
e) [3 . (70-x) + 5 ] : 2 = 46
<=> [3 . (70-x) + 5 ] = 46 . 2
<=> [3 . (70-x) + 5 ] = 92
<=> 210 - 3.x + 5 = 92
<=>210- 3.x = 92 - 5
<=> 210 - 3.x = 87
<=> 3.x = 210 - 87
<=> 3.x = 123
<=> x = 123 : 3
<=> x = 41
Vậy x = 41
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\(1\)) \(70:\frac{4x+720}{x}=\frac{1}{2}\)
\(\Leftrightarrow\frac{4x+720}{x}=70:\frac{1}{2}\)
\(\Leftrightarrow\frac{4x+720}{x}=140\)
\(\Leftrightarrow\left(4x+720\right):x=140\)
\(\Leftrightarrow4x+720=140.x\)
\(\Leftrightarrow4x-140x=-720\)
\(\Leftrightarrow x.\left(-136\right)=-720\)
\(\Leftrightarrow x=-720:\left(-136\right)\)
\(\Leftrightarrow x=\frac{90}{17}\)
\(2\)) Mình đang nghĩ
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A=1+2+3+...+70
A=(70+1).[(70-1):1+1]:2
A=71.70:2
A=4970:2
A=2485
B=5+10+15+...+100
B=(100+5).[(100-5):5+1]:2
B=105.20:2
B=2100:2
B=1050
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a. 8 + (x - 9) = 125 - 64
8 + (x - 9) = 61
x - 9 = 53
x = 62
b. 5 x (X + 7) - 10 = 8 x 5
5 x (X + 7) - 10 = 40
5 x (X + 7) = 50
X + 7 = 10
X = 3
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a,70-5.(x-3)=45
=>5.(x-3)=70-45
=>5.(x-3)=25
=>x-3=25:5
=>x-3=5
=>x=8
b,10+2x=4^5:4^3
=>10+2x=4^2
=>10+2x=16
=>2x=16-10
=>2x=6
=>x=3
a ) 70 - 5 . ( x - 3 ) = 45
5 . ( x - 3 ) = 70 - 45
5 . ( x - 3 ) = 25
x - 3 = 25 ; 5
x - 3 = 5
x = 5 + 3
x = 8
b) 10 + 2x = 45 : 43
10 + 2 x = 42
10 + 2. x = 16
2x = 16 = 10
2x = 6
x = 6 : 2
x = 3
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a) 70 - 5 .(x -3 ) =45
5 . ( x - 3 ) = 70 - 45
5 . ( x - 3 ) = 25
x - 3 = 25 : 5
x - 3 = 5
x = 5 + 3
x = 8
b) 156 - ( x + 61 )+82
sai đề ( không có kết quả )
c) 10 +2 .x = 45 : 43
10 + 2 . x = 42 = 16
2 . x = 16 -10
2 . x = 6
x = 6 : 2
x = 3
d) [(10 - x ).2 +3 ];3 -2=13
[ ( 10 - x ) . 2 + 3 ] : 3 = 13 + 2
[ ( 10 - x ) . 2 + 3 ] : 3 = 15
[ ( 10 - x ) . 2 + 3 ] = 15 x 3
[ ( 10 - x ) . 2 + 3 ] = 45
( 10 - x ) . 2 = 45 - 3
( 10 - x ) . 2 = 42
10 - x = 42 : 2
10 - x = 21
x = 10 - 21
x = - 11
hok tốt
![](https://rs.olm.vn/images/avt/0.png?1311)
\(a,210-5x=200\)
\(5x=10\)
\(x=2\)
Vậy \(x=2\)
\(b,210-5\left(x-10\right)=200\)
\(5\left(x-10\right)=10\)
\(x-10=2\)
\(x=12\)
Vậy \(x=12\)
\(c,450\div\left[41-\left(2x-5\right)\right]=3^2.5\)
\(450\div\left[41-\left(2x-5\right)\right]=45\)
\(41-\left(2x-5\right)=10\)
\(2x-5=31\)
\(2x=36\)
\(x=18\)
Vậy \(x=18\)
\(d,350\div x+10=20\)
\(350\div x=10\)
\(x=35\)
Vậy \(x=35\)
\(e,36\div\left(x-5\right)=2^2\)
\(36\div\left(x-5\right)=4\)
\(x-5=9\)
\(x=14\)
Vậy \(x=14\)
\(f,\left[3\left(70-x\right)+5\right]\div2=46\)
\(3\left(70-x\right)+5=92\)
\(3\left(70-x\right)=87\)
\(70-x=29\)
\(x=41\)
Vậy \(x=41\)
a)210-5x=200 b)210-5(x-10)=200
5x=210-200=10 5(x-10)=210-200=10
x=10:5=2 x-10 =10:5=2 c)45:[41-(2x-5)]=32.5 x =2+10=12
45:[41-(2x-5)] =9.5=45 d)350:x+10=20
41-(2x-5)=45:45=1 350:x =20-10=10
2x-5 =41-1=40 x =350:10=35
2x =40+5=45
x =45:2=22,5
e)36:(x-5)=22 f)[3.(70-x)+5]:2=46
36:(x-5)=4 [3.(70-x)+5] =46.2=92
x-5 =36:4=9 3.(70-x) =92-5=87
x =9+5=14 70-x =87:3=29
x =70-29=41
1/10 x + 70% x = 5/2
=>1/10 x + 70/100 x = 5/2
=>1/10 x + 7/10 x = 5/2
=>x.(1/10+7/10)=5/2
=>x.8/10=5/2
=>x.4/5=5/2
=>x=5/2:4/5
=>x=5/2.5/4
=>x=25/8
1/10x + 70% x = 5/2
=> 1/10x + 70/100 x = 5/2.
=> 1/10x + 7/10x = 5/2
=> x.( 1/10 + 7/10 ) = 5/2
=> x . 8/10 = 5/2
=> x . 4/5 = 5/2
=> x = 5/2 : 4/5
=> x = 5/2 x 5/4
=> x =25/8