5.

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

\(\Leftrightarrow Ax-2A\sqrt{x}+4A=2\sqrt{x}\)

\(\Leftrightarrow Ax-2A\sqrt{x}+4A=2\sqrt{x}\)

\(\Leftrightarrow Ax-2\left(A-1\right)\sqrt{x}+4A=0\)

\(\Delta'=A^2-2A+1-4A^2=-3A^2-2A+1\ge0\)

\(\Leftrightarrow\left(1-3A\right)\left(A+1\right)\ge0\)

\(\Leftrightarrow-1\le A\le\dfrac{1}{3}\)

\(A=0\left(\text{vì }A\ge0\right)\Leftrightarrow x=0\)

6.

\(P=\dfrac{4\sqrt{x}-13}{x-2\sqrt{x}+1}\)

\(\Leftrightarrow Px-2\left(P+2\right)\sqrt{x}+P+13=0\)

\(\Delta'=P^2+4P+4-P^2-13P=-9P+4\ge0\Leftrightarrow P\le\dfrac{4}{9}\)

\(P=0\Leftrightarrow4\sqrt{x}-13=0\Leftrightarrow x=\dfrac{169}{16}\)

Câu 3 : 

\(n_{H2}=\dfrac{2,24}{22,4}=0,1\left(mol\right)\)

Vì Ag không tác dụng với HCl loãng nên : 

a) Pt : \(Fe+2HCl\rightarrow FeCl_2+H_2|\)

             1        2             1           1

            0,1                                  0,1

b) \(n_{Fe}=\dfrac{0,1.1}{1}=0,1\left(mol\right)\)

\(m_{Fe}=0,1.56=5,6\left(g\right)\)

\(m_{Ag}=10-5,6=4,4\left(g\right)\)

⁰/₀Fe = \(\dfrac{5,6.100}{10}=56\)⁰/₀

⁰/₀Ag = \(\dfrac{4,4.100}{10}=44\)⁰/₀

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Mình cảm ơn bạn gấc gấc nhìu lun ạ

\(3x-2\sqrt{3x-2}=1\left(đk:x\ge\dfrac{2}{3}\right)\)

\(\Leftrightarrow2\sqrt{3x-2}=3x-1\)

\(\Leftrightarrow4\left(3x-2\right)=9x^2-6x+1\)

\(\Leftrightarrow9x^2-18x+9=0\)

\(\Leftrightarrow9\left(x-1\right)^2=0\Leftrightarrow x=1\left(tm\right)\)