Đáp án+Giải thích các bước giải:
`a)\sqrt{25(x^2-4x+4)}-1=9`
`<=> \sqrt{5^2 (x-2)^2}=10`
`<=> \sqrt{5^2}*\sqrt{(x-2)^2}=10`
`<=> 5|x-2|=10`
`<=> |x-2|=2`
`<=> x-2= ±2`
`<=>`\(\left[ \begin{array}{l}x-2=2\\x-2=-2\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x=4\\x=0\end{array} \right.\)
Vậy `S={4;0}`
`b)\sqrt{16(x^2+2x+1)}+5=13`
`<=> \sqrt{4^2 (x+1)^2}=8`
`<=> \sqrt{4^2}*\sqrt{(x+1)^2}=8`
`<=> 4|x+1|=8`
`<=> |x+1|=2`
`<=> x+1=±2`
`<=>`\(\left[ \begin{array}{l}x+1=2\\x+1=-2\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x=1\\x=-3\end{array} \right.\)
Vậy `S={1;-3}`
