\(\sqrt{\sqrt{7}-\sqrt{3}}< \sqrt{\sqrt{7}+\sqrt{3}}\Rightarrow D< 0\)
\(D^2=\frac{\sqrt{7}-\sqrt{3}+\sqrt{7}+\sqrt{3}-2\sqrt{\left(\sqrt{7}-\sqrt{3}\right)\left(\sqrt{7}+\sqrt{3}\right)}}{\sqrt{7}-2}\)
\(=\frac{2\sqrt{7}-2\sqrt{4}}{\sqrt{7}-2}=\frac{2\left(\sqrt{7}-2\right)}{\sqrt{7}-2}=2\)
\(\Rightarrow D=-\sqrt{2}\)
\(\sqrt{7-4\sqrt{3}}\) + \(\sqrt{12+6\sqrt{3}}\)
rút gọn biểu thức trên
rút gọn biểu thức
a, \(\dfrac{1}{\sqrt{7-\sqrt{24}+1}}-\dfrac{1}{\sqrt{7+\sqrt{24}+1}}\)
b,\(\sqrt{\dfrac{3+\sqrt{5}}{3-\sqrt{5}}}+\sqrt{\dfrac{3-\sqrt{5}}{3+\sqrt{5}}}\)
c,\(\dfrac{4+\sqrt{7}}{3\sqrt{2}+\sqrt{4}+\sqrt{7}}+\dfrac{4-\sqrt{7}}{3\sqrt{7}-\sqrt{4}-\sqrt{7}}\)
Rút gọn biểu thức:
\(\frac{\sqrt{7+\sqrt{5}}+\sqrt{7-\sqrt{5}}}{\sqrt{7+2\sqrt{11}}}-\sqrt{3-2\sqrt{2}}\)
Thu gọn biểu thức:
D= \(\left(\frac{\sqrt{7}-7}{1-\sqrt{7}}-\frac{\sqrt{7}+1}{7+\sqrt{7}}\right):\frac{\sqrt{7}+1}{\sqrt{7}}-7\sqrt{\frac{1}{\sqrt{7}}}\)
Rút gọn các biểu thức sau: ko tính
\(13-2\sqrt{42}\)
\(46+6\sqrt{5}\)
\(\sqrt{3-\sqrt{5}}.\left(\sqrt{10}-\sqrt{2}\right)\left(3+\sqrt{5}\right)\)
\(\sqrt{6+2\sqrt{2}.\sqrt{3-\sqrt{4+2\sqrt{3}}}}\)
\(\sqrt[]{5}-\sqrt{3-\sqrt{29-12\sqrt{5}}}\)
\(\frac{\sqrt{\sqrt{7}-\sqrt{3}}-\sqrt{\sqrt{7}+\sqrt{3}}}{\sqrt{\sqrt{7}-2}}\)
cho biểu thức:
\(P=\left(\dfrac{1-a\sqrt{a}}{1-\sqrt{a}}+\sqrt{a}\right).\left(\dfrac{1+a\sqrt{a}}{1+\sqrt{a}}-\sqrt{a}\right)\)
a) rút gọn P.
b) tìm a để P < \(7-4\sqrt{3}\)
Rút gọn biểu thức:
a) \(A=\sqrt{7-4\sqrt{3}}-\sqrt{7+4\sqrt{3}}\)
b) \(B=\left(\frac{\sqrt{x}+1}{x-4}-\frac{\sqrt{x}-1}{x+4\sqrt{x}+4}\right).\frac{x\sqrt{x}+2x-4\sqrt{x}-8}{\sqrt{x}}\) với \(x>0,x\ne4\)
Rút gọn biểu thức
\(\dfrac{1}{3-\sqrt{8}}-\dfrac{1}{\sqrt{8}-\sqrt{7}}+\dfrac{1}{\sqrt{7}-\sqrt{6}}-\dfrac{1}{\sqrt{6}-\sqrt{5}}+\dfrac{1}{\sqrt{5}-2}\)
rút gọn
\(\sqrt{2}.\sqrt{7-3\sqrt{5}}\)
