\(72-3\left|x\right|=9\)
\(3\left|x\right|=72-9=63\)
\(\left|x\right|=63:3=21\)
\(\Rightarrow x=\pm21\)
\(72-3\left|x\right|=9\)
\(3\left|x\right|=63\)
\(\left|x\right|=21\)
x= 21 hoặc x= -21
\(-12\left(x-5\right)+7\left(3-x\right)=9\)
\(-12x+60+21-7x=9\)
\(-19x=-72\)
\(x=\dfrac{72}{19}\)