Question

Answer 1

a: Ta có: \(\sqrt{4x^2-28x+49}=5\)

\(\Leftrightarrow\left|2x-7\right|=5\)

\(\Leftrightarrow\left[{}\begin{matrix}2x-7=5\\2x-7=-5\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=6\\x=1\end{matrix}\right.\)

b: Ta có: \(\dfrac{1}{2}\sqrt{x-2}-4\sqrt{\dfrac{4x-8}{9}}+\sqrt{9x-18}-5=0\)

\(\Leftrightarrow\dfrac{1}{2}\sqrt{x-2}-4\cdot\dfrac{2}{3}\cdot\sqrt{x-2}+3\sqrt{x-2}=5\)

\(\Leftrightarrow\sqrt{x-2}=6\)

hay x=38

Answer 2

\(a\sqrt{\left(7\right)^2-2.7.2x+\left(2x\right)^2}=5\)

\(\sqrt{\left(7-2x\right)^2}=5^2\)

\(7-2x=25\)

\(x=-9\)