a)\(P=\left(\sqrt{x}-\dfrac{x+3}{\sqrt{x}+1}\right):\left(\dfrac{\sqrt{x}}{\sqrt{x}+1}-\dfrac{\sqrt{x}-9}{1-x}\right)\)

\(P=\left(\dfrac{\sqrt{x}\left(\sqrt{x}+1\right)-x-3}{\sqrt{x}+1}\right):\left(\dfrac{\sqrt{x}\left(\sqrt{x}-1\right)-9+\sqrt{x}}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-1\right)}\right)\)

\(P=\left(\dfrac{\sqrt{x}-3}{\sqrt{x}+1}\right):\left(\dfrac{x-9}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-1\right)}\right)\)

\(P=\dfrac{\sqrt{x}-1}{\sqrt{x}+3}\)

b)\(x\ge0\Rightarrow\sqrt{x}\ge0\ge\sqrt{x}+3\ge3\)

\(\)\(\Rightarrow\sqrt{x}-1\ge0\Leftrightarrow x\ge1\)

Vậy \(P_{min}\) =0 tại x=1

\(x:3\dfrac{1}{5}=1\dfrac{1}{2}\)

\(\Leftrightarrow x:\dfrac{16}{5}=\dfrac{3}{2}\)

\(\Leftrightarrow x=\dfrac{16}{15}.\dfrac{3}{2}\)

\(\Leftrightarrow x=\dfrac{8}{5}\)

+) \(\dfrac{2}{5}x+\dfrac{-3}{7}=\dfrac{-1}{5}x+\dfrac{8}{14}\)

\(\Leftrightarrow\dfrac{3}{5}x=1\)

\(\Leftrightarrow x=\dfrac{5}{3}\)

rút gọn à bạn?

\(\dfrac{a-b}{\sqrt{a}-\sqrt{b}}-\dfrac{\sqrt{a^3}+\sqrt{b^3}}{a-b}\)

\(=\dfrac{\left(a-b\right)\left(\sqrt{a}+\sqrt{b}\right)-\sqrt{a^3}-\sqrt[]{b^3}}{\left(\sqrt{x}-\sqrt{b}\right)\left(\sqrt{a}+\sqrt{b}\right)}\)

\(=\dfrac{a\sqrt{a}-b\sqrt{a}+a\sqrt{b}-b\sqrt{b}-a\sqrt{a}-b\sqrt[]{b}}{\left(\sqrt{a}-\sqrt{b}\right)\left(\sqrt{a}+\sqrt{b}\right)}\)

\(=\dfrac{-b\sqrt{a}+\left(a-2b\right)\sqrt{b}}{\left(\sqrt{a}-\sqrt{b}\right)\left(\sqrt{a}+\sqrt{b}\right)}\)

\(\overset{x}{Fe}\left(\overset{I}{NO3}\right)_3\)

\(\Rightarrow x=\dfrac{I.3}{1}=3\)

=>Hóa trị III

I find the news about ancient towns interesting

\(a.2Al+3H2SO4\rightarrow Al2\left(SO4\right)3+3H2\)

b)\(n_{Al}=\dfrac{7,1}{27}=\dfrac{71}{270}\left(mol\right)\)

\(n_{H2SO4}=\dfrac{3}{2}n_{Al}=\dfrac{71}{180}\left(mol\right)\)

\(\Rightarrow V=\dfrac{71}{180}:0,05=\dfrac{71}{9}\left(l\right)\)

c)\(n_{H2}=\dfrac{3}{2}n_{Al}=\dfrac{71}{180}\left(mol\right)\)

\(V_{H2}=\dfrac{71}{180}.22,4=\dfrac{476}{225}\left(l\right)\)

Mr Vô Danh: Em có tham gia không mà đòi tăng 15 GP :v

về giải thưởng thì tuần này vẫn như các tuần trước nha mọi người

+) Nhất: 5 coin+10GP ( có thể nhiều hơn 1 người có giải)

+) giải đặc biệt: 3 coin+ 5 GP