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3x - 7 = 2x + 5
3x - 2x = 5 + 7
x = 12
|3x - 2| = 7
\(\Rightarrow\left\{\begin{matrix}3x-2=7\\-\left(3x-2\right)=7\end{matrix}\right.\Rightarrow\left\{\begin{matrix}3x=9\\-3x+2=7\end{matrix}\right.\)
\(\Rightarrow\left\{\begin{matrix}x=3\\-3x=5\end{matrix}\right.\Rightarrow\left\{\begin{matrix}x=3\\x=-\frac{5}{3}\end{matrix}\right.\)
4 - |x - 2| = -3
|x - 2| = 4 - (-3)
|x - 2| = 7
\(\Rightarrow\left\{\begin{matrix}x-2=7\\-\left(x-2\right)=7\end{matrix}\right.\Rightarrow\left\{\begin{matrix}x=9\\-x+2=7\end{matrix}\right.\)
\(\Rightarrow\left\{\begin{matrix}x=9\\-x=5\end{matrix}\right.\Rightarrow\left\{\begin{matrix}x=9\\x=-5\end{matrix}\right.\)
|2x - 3| = x - 1
\(\Rightarrow\left\{\begin{matrix}2x-3=x-1\\-\left(2x-3\right)=x-1\end{matrix}\right.\Rightarrow\left\{\begin{matrix}2x-x=-1+3\\-2x+3=x-1\end{matrix}\right.\)
\(\Rightarrow\left\{\begin{matrix}x=2\\-2x-x=-1-3\end{matrix}\right.\Rightarrow\left\{\begin{matrix}x=2\\-3x=-4\end{matrix}\right.\)
\(\Rightarrow\left\{\begin{matrix}x=2\\x=\frac{4}{3}\end{matrix}\right.\)
|3x + 1| = x + 3
\(\Rightarrow\left\{\begin{matrix}3x+1=x+3\\-\left(3x+1\right)=x+3\end{matrix}\right.\Rightarrow\left\{\begin{matrix}3x-x=3-1\\-3x-1=x+3\end{matrix}\right.\)
\(\Rightarrow\left\{\begin{matrix}2x=2\\-3x-x=3+1\end{matrix}\right.\Rightarrow\left\{\begin{matrix}x=1\\-4x=4\end{matrix}\right.\)
\(\Rightarrow\left\{\begin{matrix}x=1\\x=-1\end{matrix}\right.\)
Xét 2 trường hợp
TH1: 2x-5 \(\ge\)0=> x\(\ge\)5/2
Ta có: /2x-5/=x+1
<=> 2x-5=x+1
<=> x=6 ( t/m)
TH2: 2x-5<0=> x<5/2
Ta có: /2x-5/=x+1
<=> 5-2x=x+1
<=> x=4/3( t/m)
Vậy....
Mấy bài sau tương tự
a, ( x+ 4 ) \(⋮\) ( x-1 )
Ta có : x+4 = x-1 + 5 mà ( x-1) \(⋮\) ( x-1 ) để ( x+ 4 ) \(⋮\) ( x-1 ) thì => 4 \(⋮\) ( x-1 )
hay x-1 thuộc Ư(4) = { 1;2;4}
ta có bảng sau
x-1 | 1 | 2 | 4 |
x | 2 | 3 | 5 |
Vậy x \(\in\) { 2;3;5 }
b, (3x+7 ) \(⋮\) ( x+1 )
Ta có : 3x+7 = 3(x+1) + 4 mà 3(x+1) \(⋮\) ( x+1) để (3x+7 ) \(⋮\) ( x+1 ) thì => 4 \(⋮\) ( x+1 )
hay x+1 thuộc Ư ( 4) = { 1;2;4}
Ta có bảng sau
x+1 | 1 | 2 | 4 |
x | 0 | 1 | 3 |
Vậy x \(\in\) {0;1;3} ( mik chỉ lm đến đây thôi , thông kảm )
a , ( x + 7 ) : ( 2x - 1 )
b, ( 2x +7 ) : ( 2x -1 )
c, ( 3x + 9 ) : ( 2x + 3 )
d, ( 3x+ 8 ) : ( x - 2 )
a) ( 2x - 3 ) - ( x - 5 ) = ( x + 7 ) - ( x + 2 )
<=> 2x - 3 - x + 5 = x + 7 - x - 2
<=> x = 3
b)(7x-5)-(6x+4)=(2x+3)-(2x+1)
<=> 7x - 5 - 6x - 4 = 2x + 3 - 2x - 1
<=> x = 11
c)(9x-3)-(8x+5)=(3x+2)
<=> 9x - 3 - 8x - 5 = 3x + 2
<=> -2x = 10
<=> x = -5
d)(x+7)-(2x+3)=(3x+5)-(2x+4)
<=> x + 7 - 2x - 3 = 3x + 5 - 2x - 4
<=> -2x = -3
<=> x = 3/2
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a, \(\frac{-2}{3}x=\frac{4}{15}\)
x = \(\frac{4}{15}:\frac{-2}{3}\)
x = \(\frac{-2}{5}\)
b, x + \(\frac{1}{3}\) = \(\frac{2}{5}-\left(\frac{-1}{3}\right)\)
x = \(\frac{11}{15}-\frac{1}{3}\)
x = \(\frac{2}{5}\)
c, \(\frac{-2}{3}\)x + \(\frac{-3}{7}\) + \(\frac{1}{2}\)x = \(\frac{-5}{6}\)
\(\frac{-1}{6}\)x + \(\frac{-3}{7}\) = \(\frac{-5}{6}\)
\(\frac{-1}{6}\)x = \(\frac{-5}{6}+\frac{3}{7}\)
\(\frac{-1}{6}\)x = \(\frac{-17}{42}\)
x = \(\frac{-17}{42}:\frac{-1}{6}\)
x = \(\frac{17}{7}\)
d, 2x(x - \(\frac{1}{7}\)) = 0
\(\Rightarrow\) 2x = 0 hoặc x - \(\frac{1}{7}\) = 0
TH1: 2x = 0
x = 0
TH2: x - \(\frac{1}{7}\) = 0
x = \(\frac{1}{7}\)
Vậy x = 0; x = \(\frac{1}{7}\)
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