Bài 1 : Tìm x
a, | 1 - x | = 7
=> 1 - x = 7 hoặc 1 - x = \(-7\)
\(\left[{}\begin{matrix}1-x=7\\1-x=-7\end{matrix}\right.=>\left[{}\begin{matrix}x=-6\\x=8\end{matrix}\right.\)
Vậy x =8 hoặc x= \(-6\)
b, | 2x + 5 | =1
=>\(\left[{}\begin{matrix}2x+5=1\\2x+5=-1\end{matrix}\right.=>\left[{}\begin{matrix}2x=-4\\2x=-6\end{matrix}\right.=>\left[{}\begin{matrix}x=-2\\x=-3\end{matrix}\right.\)
Vậy x= -2 hoặc x = -3
c, | x - 5 | = 3
=>\(\left[{}\begin{matrix}x-5=3\\x-5=-3\end{matrix}\right.=>\left[{}\begin{matrix}x=8\\x=2\end{matrix}\right.\)
Vậy x = - 8 hoặc x = 2
a) \(\left|1-x\right|=7\)
\(\Leftrightarrow\left[{}\begin{matrix}1-x=7\\1-x=-7\end{matrix}\right.\)\(\Leftrightarrow\left[{}\begin{matrix}x=-6\\x=8\end{matrix}\right.\)\(\left(tm\right)\)
Vậy .........................
b) \(\left|2x+5\right|=1\)
\(\Leftrightarrow\left[{}\begin{matrix}2x+5=1\\2x+5=-1\end{matrix}\right.\)\(\Leftrightarrow\left[{}\begin{matrix}2x=-4\\2x=-6\end{matrix}\right.\)\(\Leftrightarrow\left[{}\begin{matrix}x=-2\\x=-3\end{matrix}\right.\)\(\left(tm\right)\)
Vậy .....................
c) \(\left|x-5\right|=3\)
\(\Leftrightarrow\left[{}\begin{matrix}x-5=3\\x-5=-3\end{matrix}\right.\)\(\Leftrightarrow\left[{}\begin{matrix}x=8\\x=2\end{matrix}\right.\)\(\left(tm\right)\)
Vậy.....................
