Question

giúp em câu 2, 3 đề 8 với ạ

Answer 1

Câu 2:

a) ĐKXĐ: \(x\ge0\)

\(pt\Leftrightarrow\sqrt{3x}-10\sqrt{3x}+21\sqrt{3x}=12\)

\(\Leftrightarrow12\sqrt{3x}=12\Leftrightarrow\sqrt{3x}=1\Leftrightarrow3x=1\Leftrightarrow x=\dfrac{1}{3}\left(tm\right)\)

b) ĐKXĐ: \(x\ge2\)

\(pt\Leftrightarrow2\sqrt{x-2}-4\sqrt{x-2}=-1\)

\(\Leftrightarrow-2\sqrt{x-2}=-1\Leftrightarrow\sqrt{x-2}=\dfrac{1}{2}\)

\(\Leftrightarrow x-2=\dfrac{1}{4}\Leftrightarrow x=\dfrac{9}{4}\)

Câu 3:

\(A=\dfrac{5\sqrt{x}-25x}{1-5\sqrt{x}}=\dfrac{5\sqrt{x}\left(1-5\sqrt{x}\right)}{1-5\sqrt{x}}=5\sqrt{x}\)