Đáp án + Giải thích các bước giải:
`1)`
`(4-x)^{2}-16=0`
`<=>(4-x-4)(4-x+4)=0`
`<=>-x(8-x)=0`
`<=>` \(\left[ \begin{array}{l}x=0\\8-x=0\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}x=0\\x=8\end{array} \right.\)
`2)`
`25-(3-x)^{2}=0`
`<=>(5-3+x)(5+3-x)=0`
`<=>(x+2)(8-x)=0`
`<=>` \(\left[ \begin{array}{l}x+2=0\\8-x=0\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}x=-2\\x=8\end{array} \right.\)
`3)`
`x^{2}-6x+9-16=0`
`<=>(x-3)^{2}-4^{2}=0`
`<=>(x-3-4)(x-3+4)=0`
`<=>(x-7)(x+1)=0`
`<=>` \(\left[ \begin{array}{l}x-7=0\\x+1=0\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}x=7\\x=-1\end{array} \right.\)
`4)`
`3x^{2}-6x+3-27=0`
`<=>3x^{2}-6x-24=0`
`<=>x^{2}-2x-8=0`
`<=>(x^{2}-2x+1)-9=0`
`<=>(x-1)^{2}-3^{2}=0`
`<=>(x-1-3)(x-1+3)=0`
`<=>(x-4)(x+2)=0`
`<=>` \(\left[ \begin{array}{l}x-4=0\\x+2=0\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}x=4\\x=-2\end{array} \right.\)
