Toán Lớp 9: √8/15
√x ³/27 (x>0)
√12/75
5/2 √48/49
đề bài : khử mẫu
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Toán Lớp 9: √8/15
√x ³/27 (x>0)
√12/75
5/2 √48/49
đề bài : khử mẫu
Comments ( 2 )
\sqrt {\dfrac{8}{{15}}} = \dfrac{{2\sqrt 2 }}{{\sqrt {15} }} = \dfrac{{2\sqrt 2 .\sqrt {15} }}{{15}} = \dfrac{{2\sqrt {30} }}{{15}}\\
\sqrt {\dfrac{{{x^3}}}{{27}}} = \dfrac{{x\sqrt x }}{{3\sqrt 3 }} = \dfrac{{x\sqrt {3x} }}{{3.3}} = \dfrac{{x\sqrt {3x} }}{9}\\
\sqrt {\dfrac{{12}}{{75}}} = \sqrt {\dfrac{4}{{25}}} = \dfrac{2}{5}\\
\dfrac{5}{2}\sqrt {\dfrac{{48}}{{49}}} = \dfrac{5}{2}.\sqrt {\dfrac{{16.3}}{{{7^2}}}} = \dfrac{5}{2}.\dfrac{{4\sqrt 3 }}{7} = \dfrac{{10\sqrt 3 }}{7}
\end{array}$