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7x - 5x = 28
x.7 - x.5 = 28
x.(7-5) = 28
x.2 = 28
x = 28 : 2
x = 14
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(7x + 28) . [( - 75) - 5x] = 0
* 7x + 28 = 0 * ( - 75) - 5x = 0
7x = -28 5x = -75 - 0
x = -28 : 7 5x = -75
x = -4 x = -75 : 5 = -15
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a: =>x/27+1=-2/3
=>x/27=-5/3
=>x=-45
b: \(\Leftrightarrow x-4=\dfrac{2}{5}:\dfrac{20}{21}=\dfrac{2}{5}\cdot\dfrac{21}{20}=\dfrac{42}{100}=\dfrac{21}{50}\)
=>x=221/50
c: \(\Leftrightarrow x+\dfrac{2}{3}=\dfrac{4}{60}=\dfrac{1}{15}\)
=>x=1/15-2/3=1/15-10/15=-9/15=-3/5
d: \(\Leftrightarrow x\cdot\dfrac{3}{5}=\dfrac{1}{5}-\dfrac{15}{14}\cdot\dfrac{21}{20}\)
=>\(x\cdot\dfrac{3}{5}=\dfrac{1}{5}-\dfrac{3}{2}\cdot\dfrac{3}{4}=\dfrac{1}{5}-\dfrac{9}{8}=\dfrac{-37}{40}\)
=>x=-37/24
e: =>-3/7x=84/45
=>x=-196/45
f: =>11/10x=-2/3
=>x=-20/33
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a, 117 - \(x\) = 28 - (-7)
117 - \(x\) = 28 + 7
117 - \(x\) = 35
\(x\) = 117 - 35
\(x\) = 82
b, \(x\) - (-38 - 2\(x\)) = (-3) - 8 + 2\(x\)
\(x\) + 38 + 2\(x\) = - 11 + 2\(x\)
3\(x\) + 38 = - 11 + 2\(x\)
3\(x\) - 2\(x\) = - 11 - 38
\(x\) = - 49
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28.76 + 37.28 - 28.13
= 28 . ( 76 + 37 - 13 )
= 28.100
= 2800
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28 x 76 + 24 x 28 - 28 x 20
= 28 x (76 + 24 - 20)
= 28 x 80
= 2240
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(28.76+15.28+9.28\)
= \(28.\left(76+15+9\right)\)
= \(28.100\)
= \(2800\)
Chúc bạn học tốt !!!
- 7x - 76 = - 28 - 5x
=> - 7x + 5x = - 28 + 76
=> - 2x = 48
=> x = 24
Vậy x = 24
@@ Học tốt
Chiyuki Fujito
\(\Leftrightarrow-2x=48\Leftrightarrow x=-24.\)
Vậy x = - 24.