Bài 6:
a: \(\sqrt{1-4x+4x^2}=5\)
=>\(\sqrt{\left(2x-1\right)^2}=5\)
=>|2x-1|=5
=>\(\left[\begin{array}{l}2x-1=5\\ 2x-1=-5\end{array}\right.\Rightarrow\left[\begin{array}{l}2x=6\\ 2x=-4\end{array}\right.\Rightarrow\left[\begin{array}{l}x=3\\ x=-2\end{array}\right.\)
b: \(\sqrt{\left(2x-1\right)^2}=3\)
=>|2x-1|=3
=>\(\left[\begin{array}{l}2x-1=3\\ 2x-1=-3\end{array}\right.\Rightarrow\left[\begin{array}{l}2x=4\\ 2x=-2\end{array}\right.\Rightarrow\left[\begin{array}{l}x=2\\ x=-1\end{array}\right.\)
c: ĐKXĐ: x<=4/5
\(\sqrt{4-5x}=12\)
=>\(4-5x=12^2=144\)
=>5x=4-144=-140
=>x=-28(nhận)
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