Question

Tìm x biết

a) \(x-3\sqrt{x}=0\)

b)\(5\sqrt{x}-x=0\)

Answer 1

\(a.\)

\(x-3\sqrt{x}=0\)

\(\Rightarrow\left(\sqrt{x}\right)^2-3\sqrt{x}=0\)

\(\Rightarrow\sqrt{x}.\left(\sqrt{x}-3\right)=0\)

\(\Rightarrow\left[\begin{array}{nghiempt}\sqrt{x}=0\\\sqrt{x}-3=0\end{array}\right.\)

\(\Rightarrow\left[\begin{array}{nghiempt}x=0\\\sqrt{x}=3\end{array}\right.\)

\(\Rightarrow\left[\begin{array}{nghiempt}x=0\\x=9\end{array}\right.\)

Vậy : \(x\in\left\{0;9\right\}\)