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\(30-5x⋮x\)
\(\Leftrightarrow30-5x+5x⋮x\left(\text{vì: 5x chia hết cho x}\right)\)
\(\Rightarrow30⋮x\Rightarrow x\in\left\{-1;1;-2;2;-3;3;-5;5;-6;6;-10;10;-15;15;-30;30\right\}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
BÀI \(1\):
\(\left(-1005\right).\left(x+2\right)=0\)
\(x+2=0:\left(-1005\right)\)
\(x+2=0\)
\(x=0-2\)
\(x=-2\)
BÀI \(2\):
\(x+x+x+91=-2\)
\(3x=\left(-2\right)-91\)
\(3x=-93\)
\(x=\left(-93\right):3\)
\(x=-31\)
BÀI \(3\):
\(\left|5x+1\right|=11\)
Có hai trường hợp:
\(TH^{ }1:_{ }5x+1=11\)
\(5x=11-1\)
\(5x=10\)
\(x=10:5\)
\(x=2\)
\(TH2:^{ }5x+1=-11\)
\(5x=\left(-11\right)-1\)
\(5x=-12\)
\(x=\left(-12\right):5\)
\(x=-2,4\)
\(k\)\(minh\)\(nhe\)\(.\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) 4 ⋮ x ⇒ x ∈ Ư(4)
Ư(4) = {1;2;4}
⇒ x = {1;2;4}
b) -13 ⋮ (x+2) ⇒ x + 2 ∈ Ư(-13)
Ư(-13) = {1,-1,-13,13}
⇒ x = {-1,-3,-16;11}
![](https://rs.olm.vn/images/avt/0.png?1311)
a) 1/2.x+3/5.(x-2)=3
<=>1/2.x+3/5.x-6/5=3
<=>11/10.x-6/5=3
<=>11/10x=41/10
<=>x=41/11
b) (3x-4).(5x+15)=0
<=>3x-4=0 hoặc 5x+15=0
<=>x=4/3 hoặc x=-3
![](https://rs.olm.vn/images/avt/0.png?1311)
`@` `\text {Ans}`
`\downarrow`
`a)`
`4x = 320 \div 16`
`=> 4x = 20`
`=> x = 20 \div 4`
`=> x=5`
Vậy, `x=5`
`b)`
`(x-10) \div 5 = 2`
`=> x - 10 = 2*5`
`=> x - 10 = 10`
`=> x = 10 + 10`
`=> x=20`
Vậy, `x=20`
`c)`
`(20+x) \div 5 = 25`
`=> 20+x = 25*5`
`=> 20+x = 125`
`=> x = 125 - 20`
`=> x = 105`
Vậy, `x=105.`
`@` `\text {Kaizuu lv uuu}`
![](https://rs.olm.vn/images/avt/0.png?1311)
trả lời
5x-3 -20 = 105
5x-3 = 105 + 20
5x-3 = 125
5x-3 = 53
x-3 = 3
x =3+3
x = 6
Vậy x = 6
\(20\%x+\frac{2}{5}x=x-4\)
\(x\left(20\%+\frac{2}{5}\right)=x-4\)
\(x.\frac{3}{5}=x-4\)
\(x.\frac{3}{5}-x=4\)
\(x\left(\frac{3}{5}-1\right)=4\)
\(x.\frac{-2}{5}=4\)
\(x=-10\)
P/s: Hoq chắc :<