Question

Rút gọn biểu thức A =\(\left(\dfrac{2}{\sqrt{x}-\sqrt{y}}-\dfrac{1}{\sqrt{x}-\sqrt{y}}-\dfrac{3\sqrt{x}}{x-y}\right)\)

Answer 1

Giải:

\(A=\dfrac{2}{\sqrt{x}-\sqrt{y}}-\dfrac{1}{\sqrt{x}-\sqrt{y}}-\dfrac{3\sqrt{x}}{x-y}\)

\(\Leftrightarrow A=\dfrac{1}{\sqrt{x}-\sqrt{y}}-\dfrac{3\sqrt{x}}{x-y}\)

\(\Leftrightarrow A=\dfrac{\sqrt{x}+\sqrt{y}}{\left(\sqrt{x}-\sqrt{y}\right)\left(\sqrt{x}+\sqrt{y}\right)}-\dfrac{3\sqrt{x}}{x-y}\)

\(\Leftrightarrow A=\dfrac{\sqrt{x}+\sqrt{y}}{x-y}-\dfrac{3\sqrt{x}}{x-y}\)

\(\Leftrightarrow A=\dfrac{\sqrt{x}+\sqrt{y}-3\sqrt{x}}{x-y}\)

\(\Leftrightarrow A=\dfrac{\sqrt{y}-2\sqrt{x}}{x-y}\)

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