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a) x+15 = 20-4x
=> x=1
b) 17-x=7-6x
=> x=-2
c) -12+x=5x-20
=> x=2
d) 4x-5=15-x
=> x=4
e) 9x-7=20-6x
=>x= \(\frac{9}{5}\)
g)2.(x-10)=3.(x-20)=x-4
=> x thuộc ∅
h) (x^2+2).(x-3) <0
=> x=3,...
3 ( x + 2 ) - 5 (x - 1 ) = - x + 10
=> 3x + 6 - 5x + 5 = - x + 10
=> 3x - 5x + x = 10 - 5 - 6
=> - x = -1
=> x = 1
- 4 ( 2x - 1 ) - 3 ( x + 2 ) = - 20
=> - 8x + 4 - 3x - 6 = - 20
=> - 8x - 3x = -20 - 4 + 6
=> - 11x = - 18
=> x = \(\frac{18}{11}\)
- 2 ( 3x + 2 ) - 2 ( 4x - 1 ) = 26
=> - 6x - 4 - 8x + 2 = 26
=> - 6x - 8x = 26 - 2 + 4
=> - 14x = 28
=> x = -2
\(\left(x+2\right)^2=4\)
=> \(\orbr{\begin{cases}x+2=2\\x+2=-2\end{cases}\Rightarrow\orbr{\begin{cases}x=0\\x=-4\end{cases}}}\)
\(\left(x-3\right)^2=25\)
=> \(\orbr{\begin{cases}x-3=5\\x-3=-5\end{cases}\Rightarrow\orbr{\begin{cases}x=8\\x=-2\end{cases}}}\)
- 3 ( x + 2 ) = 0
=> x + 2 = 0
=> x = -2
4 ( x - 1 ) = 0
=> x - 1 = 0
=> x = 1
\(\text{1,(-14)+(2x–4^2)=/-10/×/5/}\)
\(-14-16+2x=10.5\)
\(-30+2x=50\)
\(2x=50--30\)
\(2x=80\)
\(x=80:2\)
\(x=40\)
\(\text{2,(-100)–/x+20/=-150}\)
\(|x+20|=-100--150\)
\(|x+20|=50\)
\(\Rightarrow\orbr{\begin{cases}x+20=50\\x+20=-50\end{cases}\Leftrightarrow\orbr{\begin{cases}x=30\\x=-70\end{cases}}}\)
\(\Rightarrow x\in\left\{-70;30\right\}\)
\(\text{3)3x+16=4x–61}\)
\(3x-4x=-61-16\)
\(-x=-77\)
\(\Rightarrow x=77\)
\(\text{4,2(x–5)–3(x+6)=0}\)
\(2x-10-3x-18=0\)
\(2x-3x=0+18+10\)
\(-x=28\)
\(x=-28\)
chúc bạn học tốt
1)=>3(x-5)(2x+9)+3(x-5)=0=>(x-5)(6x+30)
=>x-5=0=>x=5
6x+30=0=>x=-5
2)=>x^2-16=0=>x=+-4
12-4x=0=>x=3
3)=>9-x^2=0=>x=+-3
4x-8=0=>x=2
4)=>8-x^3=0=>x=3
5^x-125=0=>x=2
5)=>2^x.2^x=8=>2^2x=8=>2x=3=>x=1,5
3(2x+3)(3x-5)<0
\(\Rightarrow\left(3x+3\right)\left(3x-5\right)< 0\)
Mà \(3x+3>3x-5\)
\(\Rightarrow\hept{\begin{cases}3x+3>0\\3x-5< 0\end{cases}}\)
\(\Rightarrow\hept{\begin{cases}3x>-3\\3x< 5\end{cases}}\)
\(\Rightarrow-1< x< \frac{5}{3}\)
\(2x^2-4x=2x\left(x-2\right)>0\)
\(\Rightarrow x\left(x-2\right)>0\)
\(\Rightarrow\orbr{\begin{cases}x< 0;x-2< 0\\x>0;x-2>0\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x< 0\\x>2\end{cases}}\)
a) \(x^3+4x=0\)
\(\Rightarrow x\left(x^2+4\right)=0\)
\(\Rightarrow\left[\begin{array}{nghiempt}x=0\\x^2+4=0\end{array}\right.\)
\(\Rightarrow\left[\begin{array}{nghiempt}x=0\\x^2=-4\end{array}\right.\)
\(\Rightarrow\left[\begin{array}{nghiempt}x=0\\x\in\phi\end{array}\right.\)
Vậy: \(x=0\)
b) \(2\left(5-x\right)=4x-3\)
\(\Rightarrow10-2x=4x-3\)
\(\Rightarrow10+3=4x+2x\)
\(\Rightarrow13=6x\)
\(\Rightarrow x=\frac{13}{6}\)
x3+ 4x=0
<=> x(x2+4)=0
=> x=0 hoặc x2+4=0
Mà: x2+4 >4
=>x=0
1) 2(3x + 5) - 6 = 0
2(3x + 5) = 6 + 0
2(3x + 5) = 6
3x + 5 = 6 : 2
3x + 5 = 3
3x = 5 - 3
3x = 2
x = 2 : 3
x = 2/3
2) 5x + 3(4 + 2x) = 25
11x + 12 = 25
11x = 25 - 12
11x = 13
x = 13 : 11
x = 13/11
3) 3(4x + 1) + 2(x - 1) = 105
14x + 1 = 105
14x = 105 - 1
14x = 104
x = 104 : 14
x = 104/14 = 52/7
4) 30 - [2(x - 3) - 2] = 14
[2(x - 3) - 2] = 30 - 14
[2(x - 3) - 2] = 16
2x - 8 = 16
2x = 16 + 8
2x = 24
x = 24 : 2
x = 12
5) 3(x - 8)(4x + 5) - 8(x - 8) = 0
12x2 - 89x - 56 = 0
x = 8 hoặc -7/12
6) 4x = 8
Vì: 41 = 4
42 = 16
=> x thuộc tập hợp rỗng