Question

Câu C ạ

 

 

Answer 1

b: Ta có: \(\sqrt{x^2-2x}=2-x\)

\(\Leftrightarrow x^2-2x=x^2-4x+4\)

\(\Leftrightarrow2x=4\)

hay x=2

Answer 2

ĐKXĐ: mọi \(x\)

\(\sqrt{x+4-4\sqrt{x}}-\sqrt{x+9-6\sqrt{x}}=1\)

\(\Leftrightarrow\sqrt{\left(\sqrt{x}-2\right)^2}-\sqrt{\left(\sqrt{x}-3\right)^2}-1=0\)

\(\Leftrightarrow\sqrt{x}-2-\sqrt{x}+3-1=0\)

\(\Leftrightarrow0=0\)

Vậy \(S=\left\{x\in R\right\}\)