Question

rút gọn biểu thức A=\(\dfrac{x+\sqrt{y}+\sqrt{xy}-1}{\sqrt{x}+1}:(\sqrt{x}-\sqrt{y})\)

Answer 1

Lời giải:

\(A=\frac{(x-1)+(\sqrt{y}+\sqrt{xy})}{\sqrt{x}+1}.\frac{1}{\sqrt{x}-\sqrt{y}}\\ =\frac{(\sqrt{x}-1)(\sqrt{x}+1)+\sqrt{y}(\sqrt{x}+1)}{\sqrt{x}+1}.\frac{1}{\sqrt{x}-\sqrt{y}}\\ =\frac{(\sqrt{x}+1)(\sqrt{x}-1+\sqrt{y})}{\sqrt{x}+1}.\frac{1}{\sqrt{x}-\sqrt{y}}\\ =\frac{\sqrt{x}+\sqrt{y}-1}{\sqrt{x}-\sqrt{y}}\)

Answer 2

\(A=\dfrac{x+\sqrt{y}+\sqrt{xy}-1}{\sqrt{x}+1}:\left(\sqrt{x}-\sqrt{y}\right)\)

\(=\dfrac{\left(x-1\right)+\sqrt{y}\left(\sqrt{x}+1\right)}{\sqrt{x}+1}:\left(\sqrt{x}-\sqrt{y}\right)\)

\(=\dfrac{\left(\sqrt{x}+1\right)\left(\sqrt{x}-1\right)+\sqrt{y}\left(\sqrt{x}+1\right)}{\sqrt{x}+1}:\left(\sqrt{x}-\sqrt{y}\right)\)

\(=\dfrac{\left(\sqrt{x}-1+\sqrt{y}\right)}{\sqrt{x}-\sqrt{y}}\)