a, 3+x=7
=>x=4
b, -3x+5=-22
=>-3x=-27
=>x=9
c, -3./x-1/=-9
/x-1/=3
th1: x-1=3 th2: x-1=-3
=>x=4 =>x=-2
\(a,3+x=7\)
\(x=7-3\)
\(x=4\)
Vậy \(x=4.\)
\(b,-3x+5=-22\)
\(-3x=-22-5\)
\(-3x=-27\)
\(x=\left(-27\right)\div\left(-3\right)\)
\(x=9\)
Vậy \(x=9.\)
\(c,-3\left|x-1\right|=-9\)
\(\left|x-1\right|=\left(-9\right)\div\left(-3\right)\)
\(\left|x-1\right|=3\)
\(\Rightarrow\left[{}\begin{matrix}x-1=3\\x-1=-3\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=4\\x=-2\end{matrix}\right.\)
Vậy \(x\in\left\{4;-2\right\}\)
a) \(3+x=7\Leftrightarrow x=7-3=4\)
KL: Vậy x=4
b) \(-3x+5=-22\Leftrightarrow-3x=-22-5=-27\Leftrightarrow x=\frac{-27}{-3}=9\)
KL: Vậy ...................
c) \(-3\left|x-1\right|=-9\Leftrightarrow\left[{}\begin{matrix}-3\left(x-1\right)=-9\\-3\left(1-x\right)=-9\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x-1=\frac{-9}{-3}=3\\1-x=\frac{-9}{-3}=3\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=4\\x=-2\end{matrix}\right.\)
KL: Vậy................
a/ 3 + x = 7
\(\Leftrightarrow\) x = 7 - 3
\(\Leftrightarrow\) x = 4.
Vậy x = 4.
b/ -3x + 5 = -22
\(\Leftrightarrow\) -3x = (-22) - 5
\(\Leftrightarrow\) -3x = -27
\(\Leftrightarrow\) x = (-27) : (-3)
\(\Leftrightarrow\) x = 9.
Vậy x = 9.
c/ -3.|x-1| = -9
\(\Leftrightarrow\) | x-1| = (-9) : (-3)
\(\Leftrightarrow\) |x -1| = 3
\(\Rightarrow\) x - 1 = 3 hoặc x - 1 = -3
\(\Leftrightarrow\) x - 1 = 3 \(\Leftrightarrow\) x - 1 = -3
\(\Leftrightarrow\) x = 3 + 1 \(\Leftrightarrow\) x = (-3) + 1
\(\Leftrightarrow\) x = 4. \(\Leftrightarrow\) x = -2.
\(\Leftrightarrow\) \(\left[{}\begin{matrix}x=4\\x=-2\end{matrix}\right.\)
Vậy x = 4 hoặc x = -2.
