Question

\(3\sqrt{x-3}=6\)

Answer 1

\(3\sqrt{x-3}=6\) (ĐK: \(x\ge3\))

\(\Leftrightarrow\sqrt{x-3}=\dfrac{6}{3}\)

\(\Leftrightarrow\sqrt{x-3}=2\)

\(\Leftrightarrow x-3=2^2\)

\(\Leftrightarrow x-3=4\)

\(\Leftrightarrow x=4+3\)

\(\Leftrightarrow x=7\left(tm\right)\)

Vậy: ... 

Answer 2

\(3\sqrt{x-3}=6\\ \Leftrightarrow\sqrt{x-3}=6:3\\ \Leftrightarrow\sqrt{x-3}=2\\ \Leftrightarrow\left(\sqrt{x-3}\right)^2=2^2\\ \Leftrightarrow x-3=4\\ \Leftrightarrow x=4+3\\ \Leftrightarrow x=7.\)