Question

a,\(\sqrt{x^2-6x+9}=3\)     b,\(\sqrt{4x+20}+\sqrt{x+5}-\dfrac{1}{3}\sqrt{9x+45}=4\)

Answer 1

a) \(pt\Leftrightarrow\sqrt{\left(x-3\right)^2}=3\Leftrightarrow\left|x-3\right|=3\)

\(\Leftrightarrow\left[{}\begin{matrix}x-3=3\\x-3=-3\end{matrix}\right.\)\(\Leftrightarrow\left[{}\begin{matrix}x=6\\x=0\end{matrix}\right.\)

b) ĐKXĐ: \(x\ge-5\)

\(pt\Leftrightarrow2\sqrt{x+5}+\sqrt{x+5}-\sqrt{x+5}=4\)

\(\Leftrightarrow2\sqrt{x+5}=4\Leftrightarrow\sqrt{x+5}=2\)

\(\Leftrightarrow x+5=4\Leftrightarrow x=-1\left(tm\right)\)