a. $A=\sqrt{\left(1-\sqrt3\right)^2}-\sqrt{\left(\sqrt3+2\right)^2}$
b. $B=\sqrt{\left(2-\sqrt3\right)^2}+\sqrt{4-2\sqrt3}$
c. $C=\sqrt{15-6\sqrt6}+\sqrt{33-12\sqrt6}$
d. $D=\sqrt{2-\sqrt3}-\sqrt{2+\sqrt3}$
e. $E=\sqrt{\dfrac{3-\sqrt5}{3+\sqrt5}}-\sqrt{\dfrac{3+\sqrt5}{3-\sqrt5}}$
f. $F=\left(\dfrac{1}{3-\sqrt5}-\dfrac{1}{3+\sqrt5}\right):\dfrac{5-\sqrt5}{\sqrt5-1}$
g. $G=\sqrt{3+\sqrt5}+\sqrt{7-3\sqrt5}-\sqrt2$
h. $H=\sqrt{x+2\sqrt{2x-4}}+\sqrt{x-2\sqrt{2x-4}}$
a.
$A=\sqrt{\left(1-\sqrt3\right)^2}-\sqrt{\left(\sqrt3+2\right)^2}=\sqrt3-1-\sqrt3-2=-3$
b.
$B=\sqrt{\left(2-\sqrt3\right)^2}+\sqrt{4-2\sqrt3}=2-\sqrt3+\sqrt{\left(\sqrt3-1\right)^2}=2-\sqrt3+\sqrt3-1=1$
c.
$C=\sqrt{15-6\sqrt6}+\sqrt{33-12\sqrt6}=\sqrt{\left(3-\sqrt6\right)^2}+\sqrt{\left(2\sqrt6-3\right)^2}=3-\sqrt6+2\sqrt6-3=\sqrt6$
d.
$\sqrt2D=\sqrt{4-2\sqrt3}-\sqrt{4+2\sqrt3}=\sqrt{\left(\sqrt3-1\right)^2}-\sqrt{\left(\sqrt3+1\right)^2}=\sqrt3-1-\sqrt3-1=-2$
$\Rightarrow D=-\sqrt2$
e.
$E=\sqrt{\dfrac{3-\sqrt5}{3+\sqrt5}}-\sqrt{\dfrac{3+\sqrt5}{3-\sqrt5}}\\=\sqrt{\dfrac{\left(3-\sqrt5\right)^2}{\left(3+\sqrt5\right)\left(3-\sqrt5\right)}}-\sqrt{\dfrac{\left(3-\sqrt5\right)^2}{\left(3+\sqrt5\right)\left(3-\sqrt5\right)}}\\=\sqrt{\dfrac{\left(3-\sqrt5\right)^2}{4}}-\sqrt{\dfrac{\left(3+\sqrt5\right)^2}{4}}\\=\dfrac{3-\sqrt5}2-\dfrac{3+\sqrt5}2\\=-\sqrt5$
f.
$F=\left(\dfrac{1}{3-\sqrt5}-\dfrac{1}{3+\sqrt5}\right):\dfrac{5-\sqrt5}{\sqrt5-1}\\=\left(\dfrac{3+\sqrt5}{\left(3-\sqrt5\right)\left(3+\sqrt5\right)}-\dfrac{3-\sqrt5}{\left(3-\sqrt5\right)\left(3+\sqrt5\right)}\right):\dfrac{\sqrt5\left(\sqrt5-1\right)}{\sqrt5-1}\\=\dfrac{3+\sqrt5-3+\sqrt5}4:\sqrt5\\=\dfrac{\sqrt5}2:\sqrt5\\=\dfrac12$
g.
$\sqrt2G=\sqrt{6+2\sqrt5}+\sqrt{14-6\sqrt5}-2=\sqrt{\left(\sqrt5+1\right)^2}+\sqrt{\left(3-\sqrt5\right)^2}-2=\sqrt5+1+3-\sqrt5-2=2$
$\Rightarrow G=\sqrt2$
h.
$\sqrt2H=\sqrt{2x-4+4\sqrt{2x-4}+4}+\sqrt{2x-4\sqrt{2x-4}+4}\\=\sqrt{\left(\sqrt{2x-4}+2\right)^2}+\sqrt{\left(\sqrt{2x-4}-2\right)^2}\\=\sqrt{2x-4}+2+|\sqrt{2x-4}-2|$
Nếu $2\le x\le 4$ thì $\sqrt2H=\sqrt{2x-4}+2+2-\sqrt{2x-4}=4\Rightarrow H=\sqrt2$
Nếu $x>4$ thì $\sqrt2H=\sqrt{2x-4}+2+\sqrt{2x-4}-2=2\sqrt{2x-4}\Rightarrow H=\sqrt{4x-8}$
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