Question

Cho x, y là các số thực dương. Rút gọn các biểu thức sau:

a) \(A = \frac{{{x^{\frac{1}{3}}}\sqrt y  + {y^{\frac{1}{3}}}\sqrt x }}{{\sqrt[6]{x} + \sqrt[6]{y}}};\)                            

b) \(B = {\left( {\frac{{{x^{\sqrt 3 }}}}{{{y^{\sqrt 3  - 1}}}}} \right)^{\sqrt 3  + 1}}.\frac{{{x^{ - \sqrt 3  - 1}}}}{{{y^{ - 2}}}}.\)

Answer 1

a: \(A=\dfrac{x^{\dfrac{1}{3}}\cdot y^{\dfrac{1}{2}}+y^{\dfrac{1}{3}}\cdot x^{\dfrac{1}{2}}}{x^{\dfrac{1}{6}}+y^{\dfrac{1}{6}}}=\dfrac{x^{\dfrac{1}{3}}\cdot y^{\dfrac{1}{3}}\left(x^{\dfrac{1}{6}}+y^{\dfrac{1}{6}}\right)}{x^{\dfrac{1}{6}}+y^{\dfrac{1}{6}}}=x^{\dfrac{1}{3}}\cdot y^{\dfrac{1}{3}}=\left(xy\right)^{\dfrac{1}{3}}\)

b: \(B=\dfrac{x^{3+\sqrt{3}}}{y^2}\cdot\dfrac{x^{-\sqrt{3}-1}}{y^{-2}}=\dfrac{x^{3+\sqrt{3}-\sqrt{3}-1}}{y^{2-2}}=x^2\)