72 –3.|x + 1| = 9
3.|x+1|=72-9
3.|x+1|=63
|x+1|=63:3
|x+1|=21
=> x+1= 21 hoặc x+1= -21
=>x = 21-1 hoặc x= -21-1
=>x =20 hoặc x=-22
Vậy x= 20 hoặc x= -22
~~ học tôt~~
\(72-3.\left|x-1\right|=9\)
\(3.\left|x-1\right|=72-9\)
\(3.\left|x-1\right|=63\)
\(\left|x-1\right|=63:3\)
\(\left|x-1\right|=21\)
Vì \(\left|x-1\right|=21\)
Nên ta có hai trường hợp
\(x-1=21\) hoặc \(x-1=-21\)
\(x=21+1\) \(x=\left(-21\right)+1\)
\(x=22\) \(x=-20\)
Vậy \(x=22\) hoặc \(x=-20\)
\(72-3\left|x+1\right|=9\)
\(\Rightarrow3\left|x+1\right|=72-9\)
\(\Rightarrow3\left|x+1\right|=63\)
\(\Rightarrow\left|x+1\right|=63:3\)
\(\Rightarrow\left|x+1\right|=21\)
\(\Rightarrow\left[{}\begin{matrix}x+1=21\\x+1=-21\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=20\\x=-22\end{matrix}\right.\)
