Ta có:
\(72-3\left|x+1\right|=9.\)
\(\Rightarrow\) \(3\left|x+1\right|=72-9.\)
\(3\left|x+1\right|=63.\)
\(\Rightarrow\left|x+1\right|=63:3.\)
\(\left|x+1\right|=21.\)
\(\Leftrightarrow\left[{}\begin{matrix}x+1=21\\x+1=-21\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=21-1=20\in Z.\\x=-21-1=-22\in Z.\end{matrix}\right.\)
Vậy: \(\left[{}\begin{matrix}x=21.\\x=-22.\end{matrix}\right.\)
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72-3.\(|x+1|\)=9
=>\(|x+1|\)=72-9
=>\(|x+1|\)=63
=>x+1=63 hoặc x+1=-63
=>x=63-1 hoặc x=-63 -1
=>x=62 hoặc x=-64
Vậy x\(\in\left\{62,-64\right\}\)
\(72-3\left|x+1\right|=9\)
\(3\left|x+1\right|=72-9\)
\(3\left|x+1\right|=63\)
\(\left|x+1\right|=\dfrac{63}{3}\)
\(\left|x+1\right|=21\)
\(\circledast\)TH1: \(x+1=21\\ x=21-1\\ x=20\)
\(\circledast\)TH2: \(x+1=-21\\ x=-21-1\\ x=-22\)
Vậy \(x\in\left\{20;-22\right\}\)
