Toán Lớp 9: Rút gọn:căn x^3+căn y^3/căn x+căn y -căn xy
giúp mik vs ạ
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Toán Lớp 9: Rút gọn:căn x^3+căn y^3/căn x+căn y -căn xy
giúp mik vs ạ
Comments ( 2 )
\dfrac{{\sqrt {{x^3}} + \sqrt {{y^3}} }}{{\sqrt x + \sqrt y }} – \sqrt {xy} \\
= \dfrac{{{{\sqrt x }^3} + {{\sqrt y }^3}}}{{\sqrt x + \sqrt y }} – \sqrt {xy} \\
= \dfrac{{\left( {\sqrt x + \sqrt y } \right)\left( {{{\sqrt x }^2} – \sqrt {xy} + {{\sqrt y }^2}} \right)}}{{\sqrt x + \sqrt y }} – \sqrt {xy} \\
= \left( {{{\sqrt x }^2} – \sqrt {xy} + {{\sqrt y }^2}} \right) – \sqrt {xy} \\
= {\sqrt x ^2} – 2\sqrt {xy} + {\sqrt y ^2}\\
= {\left( {\sqrt x – \sqrt y } \right)^2}
\end{array}\)