A) \(\sqrt{4\left(1-x\right)^2}-6=0\)
\(\sqrt{4\left(1-x\right)^2}=6\)
\(\hept{\begin{cases}4\left(1-x\right)=6\\4\left(1-x\right)=-6\end{cases}}\)
\(\hept{\begin{cases}x=-\frac{1}{2}\\x=\frac{5}{2}\end{cases}}\)
B)\(\sqrt{1-12x+36x^2}=5\)
\(\sqrt{\left(1-6x\right)^2}=5\)
\(\hept{\begin{cases}1-6x=5\\1-6x=-5\end{cases}}\)
\(\hept{\begin{cases}x=-\frac{2}{3}\\x=1\end{cases}}\)