\(H=\dfrac{x+5\sqrt{x}+6+x-3\sqrt{x}+2-4\sqrt{x}+4}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+2\right)}:\dfrac{\sqrt{x}-2+5}{\sqrt{x}-2}\)

\(=\dfrac{2x-2\sqrt{x}+12}{\sqrt{x}+2}\cdot\dfrac{1}{\sqrt{x}+3}\)

\(I=\dfrac{3x+3-2x+6\sqrt{x}-x-3\sqrt{x}}{x-9}:\dfrac{2\sqrt{x}-2-\sqrt{x}+3}{\sqrt{x}-3}\)

\(=\dfrac{3\left(\sqrt{x}+1\right)}{\left(\sqrt{x}-3\right)\left(\sqrt{x}+3\right)}\cdot\dfrac{\sqrt{x}-3}{\sqrt{x}+1}=\dfrac{3}{\sqrt{x}+3}\)

\(X=\dfrac{3}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+1\right)}+\dfrac{2}{\sqrt{x}+1}+\dfrac{1}{2-\sqrt{x}}\left(đk:x\ge0;x\ne4\right)\)

\(X=\dfrac{3}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+1\right)}+\dfrac{2}{\sqrt{x}+1}-\dfrac{1}{\sqrt{x}-2}\)

\(X=\dfrac{3}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+1\right)}+\dfrac{2\left(\sqrt{x}-2\right)}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+1\right)}-\dfrac{\sqrt{x}+1}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+1\right)}\)

\(X=\dfrac{3+2\sqrt{x}-4-\sqrt{x}-1}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+1\right)}\)

\(X=\dfrac{\sqrt{x}-2}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+1\right)}\)

\(X=\dfrac{1}{\sqrt{x}+1}\)

\(S=\left(\dfrac{1}{x+2\sqrt{x}}+\dfrac{1}{\sqrt{x}-2}\right):\left(\dfrac{1-\sqrt{x}}{x+4\sqrt{x}+4}\right)\left(đk:x\ge0;x\ne1\right)\)

\(S=\left(\dfrac{\sqrt{x}-2}{\sqrt{x}\left(\sqrt{x}+2\right)\left(\sqrt{x}-2\right)}+\dfrac{\sqrt{x}\left(\sqrt{x}+2\right)}{\sqrt{x}\left(\sqrt{x}+2\right)\left(\sqrt{x}-2\right)}\right):\left(\dfrac{1-\sqrt{x}}{x+4\sqrt{x}+4}\right)\)

\(S=\dfrac{\sqrt{x}-2+x+2\sqrt{x}}{\sqrt{x}\left(\sqrt{x}+2\right)\left(\sqrt{x}-2\right)}.\dfrac{x+4\sqrt{x}+4}{1-\sqrt{x}}\)

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

\(S=\dfrac{\left(x+3\sqrt{x}-2\right)\left(\sqrt{x}+2\right)}{\sqrt{x}\left(\sqrt{x}-2\right)\left(1-\sqrt{x}\right)}\)

(đến đoạn này thì trong ngoặc ko tách ra đc nữa nên mik nghĩ là đến đây là xong, nếu sai thì bn nói mik)

\(K=\dfrac{\sqrt{x}-1}{2\sqrt{x}+1}-\dfrac{3}{1-2\sqrt{x}}-\dfrac{4\sqrt{x}+4}{4x-1}\left(đk:x\ge0\right)\)

\(K=\dfrac{\sqrt{x}-1}{2\sqrt{x}+1}+\dfrac{3}{2\sqrt{x}-1}-\dfrac{4\sqrt{x}+4}{4x-1}\)

\(K=\dfrac{\left(\sqrt{x}-1\right)\left(2\sqrt{x}-1\right)}{\left(2\sqrt{x}+1\right)\left(2\sqrt{x}-1\right)}+\dfrac{3\left(2\sqrt{x}+1\right)}{\left(2\sqrt{x}+1\right)\left(2\sqrt{x}-1\right)}-\dfrac{4\sqrt{x}+4}{\left(2\sqrt{x}+1\right)\left(2\sqrt{x}-1\right)}\)

\(K=\dfrac{2x-3\sqrt{x}+1}{\left(2\sqrt{x}+1\right)\left(2\sqrt{x}-1\right)}+\dfrac{6\sqrt{x}+3}{\left(2\sqrt{x}+1\right)\left(2\sqrt{x}-1\right)}-\dfrac{4\sqrt{x}+4}{\left(2\sqrt{x}+1\right)\left(2\sqrt{x}-1\right)}\)

\(K=\dfrac{2x-3\sqrt{x}+1+6\sqrt{x}+3-4\sqrt{x}-4}{\left(2\sqrt{x}+1\right)\left(2\sqrt{x}-1\right)}\)

\(K=\dfrac{2x-\sqrt{x}}{\left(2\sqrt{x}+1\right)\left(2\sqrt{x}-1\right)}\)

\(K=\dfrac{\sqrt{x}}{2\sqrt{x}+1}\)

\(b,\dfrac{\sqrt{12}-\sqrt{6}}{\sqrt{30}-\sqrt{15}}=\dfrac{\sqrt{6}\left(\sqrt{2}-1\right)}{\sqrt{15}\left(\sqrt{2}-1\right)}=\dfrac{\sqrt{6}}{\sqrt{15}}=\dfrac{\sqrt{2}}{\sqrt{5}}\)

\(d,\dfrac{ab-bc}{\sqrt{ab}-\sqrt{bc}}=\dfrac{\left(\sqrt{ab}-\sqrt{bc}\right)\left(\sqrt{ab}+\sqrt{bc}\right)}{\left(\sqrt{ab}-\sqrt{bc}\right)}=\sqrt{ab}+\sqrt{bc}=\sqrt{b}\left(\sqrt{a}+\sqrt{c}\right)\)

\(e,\left(a\sqrt{\dfrac{a}{b}+2\sqrt{ab}}+b\sqrt{\dfrac{a}{b}}\right)\sqrt{ab}\)

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

\(=a\sqrt{a}\sqrt{a+2b\sqrt{ab}}+b\sqrt{a^2}\)

\(=a\sqrt{a^2+2ab\sqrt{ab}}+ab\)

\(=a\left(\sqrt{a^2+2ab\sqrt{ab}}+b\right)\)

\(f,\left(\dfrac{1-a\sqrt{a}}{1-\sqrt{a}}+\sqrt{a}\right)\left(\dfrac{1+a\sqrt{a}}{1+\sqrt{a}}-\sqrt{a}\right)\)

\(=\left(a+\sqrt{a}+1+\sqrt{a}\right)\left(a-\sqrt{a}+1-\sqrt{a}\right)\)

\(=\left(a+2\sqrt{a}+1\right)\left(a-2\sqrt{a}+1\right)\)

\(=\left(\sqrt{a}+1\right)^2\left(\sqrt{a}-1\right)^2\)

\(=\left(a-1\right)^2=a^2-2a+1\)

\(P=\left(x-y\right)^2+\left(x+y\right)^2-2\left(x-y\right)\left(x+y\right)-4x^2\\ P=\left(x-y-x-y\right)^2-4x^2\\ P=4y^2-4x^2=4\left(y-x\right)\left(x+y\right)\)

`4(x-6)-x^2 (2+3x)+x(5x-4)+3x^2 (x-1)`

`=4x-24-2x^2 -3x^3 +5x^2-4x+3x^3-3x^2`

`=-24`

\(4\left(x-6\right)-2x\left(2+3x\right)+x\left(5x-4\right)+3x2\left(x-1\right)\\ =4x-24-4x-6x^2+5x^2-4x+6x^2+6x\\ =2x+5x^2-24\)

a, \(9x+3x\left(2x^2+x-3\right)=9x+6x^3+3x^2-9x\)

b, \(\left(3x-1\right)^2-9x\left(x+1\right)=9x^2-6x+1-9x^2-9x=1-15x\)

c, \(\left(x-1\right)^2-x\left(x+1\right)=x^2-2x+1-x^2-x=1-3x\)

a) \(5\sqrt{\dfrac{1}{5}}+\dfrac{1}{3}\sqrt{45}+\dfrac{5-\sqrt{5}}{\sqrt{5}}=\sqrt{5}+\sqrt{5}+\dfrac{\sqrt{5}\left(\sqrt{5}-1\right)}{\sqrt{5}}=\sqrt{5}+\sqrt{5}+\sqrt{5}-1=-1+3\sqrt{5}\)

b) \(\sqrt{7-4\sqrt{3}}+\sqrt{\left(1+\sqrt{3}\right)^2}=\sqrt{\left(2-\sqrt{3}\right)^2}+1+\sqrt{3}=2-\sqrt{3}+1+\sqrt{3}=3\)

a: \(5\sqrt{\dfrac{1}{5}}+\dfrac{1}{3}\sqrt{45}+\dfrac{5-\sqrt{5}}{\sqrt{5}}\)

\(=\sqrt{5}+\sqrt{5}+\sqrt{5}-1\)

\(=3\sqrt{5}-1\)

b: \(\sqrt{7-4\sqrt{3}}+\sqrt{\left(\sqrt{3}+1\right)^2}\)

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

=3

Đk: \(x\ge4\)

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

\(=\sqrt{\left(x-4\right)+4\sqrt{x-4}+4}+\sqrt{\left(x-4\right)-4\sqrt{x-4}+4}\)

\(=\sqrt{\left(\sqrt{x-4}+2\right)^2}+\sqrt{\left(\sqrt{x-4}-2\right)^2}\)

\(=\sqrt{x-4}+2+\left|\sqrt{x-4}-2\right|\)

TH1:\(\sqrt{x-4}>2\Leftrightarrow x>8\)

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

TH2:\(\sqrt{x-4}\le2\Leftrightarrow4\le x\le8\)

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

Vậy...

\(A=\left(\dfrac{\sqrt{x}-2}{x-1}-\dfrac{\sqrt{x}+2}{x+2\sqrt{x}+1}\right)\cdot\dfrac{\left(x-1\right)^2}{2}\)

\(=\dfrac{x-\sqrt{x}-2-\sqrt{x}-\sqrt{x}+2}{\left(\sqrt{x}-1\right)^2\cdot\left(\sqrt{x}+1\right)}\cdot\dfrac{\left(x-1\right)^2}{2}\)

\(=-\sqrt{x}\cdot\left(\sqrt{x}+1\right)\)