Rút gọn:
\(A=\left(\frac{4x\sqrt{x}+3x+9}{x+5\sqrt{x}+6}-\frac{3-\sqrt{x}}{2+\sqrt{x}}\right)\div\left(\frac{\sqrt{x}}{3+\sqrt{x}}-\frac{3+4\sqrt{x}}{x+5\sqrt{x}+6}\right)\)
\(B=\left(x-\sqrt{x}-2\right)\left(\dfrac{3}{\sqrt{x}-2}-\dfrac{4-\sqrt{x}}{x-2\sqrt{x}}\right)\)
.Làm ngắn các câu sau
a)\(\left(5+2\sqrt{6}\right)\left(49-20\sqrt{6}\right)\sqrt{5-2\sqrt{6}}\)
b) \(\frac{\sqrt{3-\sqrt{5}}.\left(3+\sqrt{5}\right)}{\sqrt{10}+\sqrt{2}}\)
1.Rút gọn:
a) \(A=\sqrt{2+\sqrt{3}.}\sqrt{2+\sqrt{2+\sqrt{3}}}.\sqrt{2-\sqrt{2+\sqrt{3}}}\)
b) \(B=\left(\frac{\sqrt{x}}{\sqrt{xy}-y}-\frac{\sqrt{y}}{\sqrt{xy}-x}\right).\left(x\sqrt{y}-y\sqrt{x}\right)\)
c) \(C=\sqrt{\left(3-\sqrt{5}\right)^2+\sqrt{6}-2\sqrt{5}}\)
Chứng minh : \(\frac{1}{\left(\sqrt{2}+\sqrt{5}\right)^3}+\frac{1}{\left(\sqrt{5}+\sqrt{8}\right)^3}\)\(+...+\frac{1}{\left(\sqrt{2006}+\sqrt{2009}\right)^3}\)\(< \frac{11}{135}\)
Rút gọn:
\(A=\left(\frac{2+\sqrt{x}}{x-5\sqrt{x}+6}-\frac{\sqrt{x}+3}{2-\sqrt{x}}-\frac{\sqrt{x}+2}{\sqrt{x}-3}\right):\left(2-\frac{\sqrt{x}}{1+\sqrt{x}}\right)\)
Tìm x để B=3A,biếtA=\(\left(\frac{5+2\sqrt{6}}{\sqrt{3}+\sqrt{2}}+\frac{5-2\sqrt{6}}{\sqrt{3}-\sqrt{2}}\right)\) /\(\left(\frac{1}{2\sqrt{5}+3\sqrt{2}}-\frac{1}{2\sqrt{5}-3\sqrt{2}}\right)\)
B=\(\frac{2x^4-x^3+2x^2+x-4}{2x^3-x^2-2x+1}\)
a/\(\frac{5-2\sqrt{5}}{\sqrt{5}}+\frac{20}{5+\sqrt{5}}\)
b/\(\frac{3+2\sqrt{3}}{\sqrt{3}}+\frac{2+\sqrt{2}}{\sqrt{2}}-\left(\sqrt{3}+\sqrt{2}\right)\)
\(\frac{\sqrt{a^3+2a^2b}+\sqrt{a^4+2a^3b}-\sqrt{a^3}-a^2b}{\sqrt{\left(2a+b-\sqrt{a^2+2ab}\right)}.\left(\sqrt[3]{a^2}-\sqrt[6]{a^5}+a\right)}\)
\(\left(1+\frac{11-\sqrt{11}}{1-\sqrt{11}}\right)\left(\frac{11+\sqrt{11}}{1+\sqrt{11}}+1\right)\)