Question

 

Mn giúp mik câu này với, cảm mơn mn nhìu

Answer 1

\(Q=x-2-2\sqrt{x-2}+4\)

\(=\left(\sqrt{x-2}-1\right)^2+3>=3\)

Dấu = xảy ra khi x=3

Answer 2

\(Q=x+2-2\sqrt{x-2} \)

\(Q=x-2-2\sqrt{x-2}+4 \)

\(Q=(\sqrt{x-2}-1)^2+3\)

Vì \((\sqrt{x-2}-1)^2\)\(\ge\)\(0\)

\(\Leftrightarrow\)\((\sqrt{x-2}-1)^2+3\)\(\ge3\)

Vậy GTNN Q=3