a) `|x+2|=3`
`⇒`\(\left[ \begin{array}{l}x+2=3\\x+2=-3\end{array} \right.\)
`⇒`\(\left[ \begin{array}{l}x=1\\x+2=-5\end{array} \right.\)
b)`x^2-2x+1=0`
`⇒x^2-x-x+1=0`
`⇒(x^2-x)-(x-1)=0`
`⇒x(x-1)-(x-1)=0`
`⇒(x-1)(x-1)=0`
`⇒(x-1)^2=0`
`⇒x-1=0`
`⇒x=1`
c) `|x+2|<4`
`⇒`\(\left[ \begin{array}{l}x+2<4\\x+2>-4\end{array} \right.\)
`⇒`\(\left[ \begin{array}{l}x<2\\x>-6\end{array} \right.\)