Tim x biết |2x-1| = x+4
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\(\left|2x-1\right|-x=4\Leftrightarrow\left|2x-1\right|=4+x\) (1)
+)TH1: \(2x-1\ge0\Leftrightarrow x\ge\frac{1}{2}\) thì ph(1) trở thành
\(2x-1=4+x\Leftrightarrow x=5\) (tm)
+)TH2: \(2x-1< 0\Leftrightarrow x< \frac{1}{2}\) thì pt(1) trở thành
\(1-2x=4+x\Leftrightarrow-3x=3\Leftrightarrow x=-1\) (tm)
Vậy x={-1;5}
|x-3|+1=x
|x+3| = x-1
Th1: x+3 = x-1
0x = 4
x thuộc rỗng
Th2: -(x+3) = x-1
-x -3 = x-1
2x = -2
x= -1
Vậy x=-1
|x-3|=2x+4
Th1: x-3 = 2x +4
x = -7
Th2: -(x-3) = 2x+4
-x +3 = 2x +4
-3x = 1
x= -1/3
Vậy x= -7; x= -1/3
|3-2x|=x+1
Th1: 3 - 2x = x+1
3x = 2
x= 2/3
Th2: - (3-2x) = x+1
- 3 +2x = x+1
x= 4
Vậy x= 2/3 và x= 4
|x-1|+3x=1
|x+1| = 1- 3x
Th1: x+1 = 1- 3x
4x = 0
x=0
Th2: -(x+1) = 1- 3x
-x -1 = 1- 3x
2x = 2
x=1
Vậy x=0 và x=1
\(3x+4=0\Leftrightarrow x=-\dfrac{4}{3}\\ 2x\left(x-1\right)-\left(1+2x\right)=-34\\ \Leftrightarrow2x^2-2x-1-2x=-34\\ \Leftrightarrow2x^2-4x+33=0\\ \Leftrightarrow2\left(x^2-2x+1\right)+30=0\\ \Leftrightarrow2\left(x-1\right)^2+30=0\\ \Leftrightarrow x\in\varnothing\left[2\left(x-1\right)^2+30\ge30>0\right]\\ x^2+9x-10=0\\ \Leftrightarrow x^2-x+10x-10=0\\ \Leftrightarrow\left(x-1\right)\left(x+10\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=1\\x=-10\end{matrix}\right.\\ \left(7x-1\right)\left(2+5x\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}7x-1=0\\2+5x=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{7}\\x=-\dfrac{2}{5}\end{matrix}\right.\)
\(\left(x+3\right)\left(2x-4\right)< 0\)
\(\Rightarrow2\left(x+3\right)\left(x-2\right)< 0\)
\(\Rightarrow\left[{}\begin{matrix}\left[{}\begin{matrix}x+3>0\\x-2< 0\end{matrix}\right.\\\left[{}\begin{matrix}x+3< 0\\x-2>0\end{matrix}\right.\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}\left[{}\begin{matrix}x>-3\\x< 2\end{matrix}\right.\\\left[{}\begin{matrix}x< -3\\x>2\end{matrix}\right.\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x>-3\\x< 2\end{matrix}\right.\)
\(\Rightarrow-3< x< 2\)
Bài 2:
a: \(\Leftrightarrow\left(x-2\right)\left(x+1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=2\\x=-1\end{matrix}\right.\)
\(\left(x+\frac{2}{3}\right)\left(\frac{5}{4}-2x\right)>0\)
th1 :
\(\hept{\begin{cases}x+\frac{2}{3}>0\\\frac{5}{4}-2x>0\end{cases}\Rightarrow\hept{\begin{cases}x>-\frac{2}{3}\\-2x>-\frac{5}{4}\end{cases}\Rightarrow}\hept{\begin{cases}x>-\frac{2}{3}\\x>\frac{5}{8}\end{cases}\Rightarrow}x>\frac{5}{8}}\)
th2 :
\(\hept{\begin{cases}x+\frac{2}{3}< 0\\\frac{5}{4}-2x< 0\end{cases}\Rightarrow\hept{\begin{cases}x< -\frac{2}{3}\\-2x< -\frac{5}{4}\end{cases}\Rightarrow}\hept{\begin{cases}x< -\frac{2}{3}\\x< \frac{5}{8}\end{cases}\Rightarrow}x< -\frac{2}{3}}\)
vậy_
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