a: \(\dfrac{1}{3}\cdot\sqrt{72}-3\sqrt{50}-\dfrac{\sqrt{66}}{\sqrt{33}}\)
\(=\dfrac{1}{3}\cdot6\sqrt{2}-3\cdot5\sqrt{2}-\sqrt{2}\)
\(=2\sqrt{2}-15\sqrt{2}-\sqrt{2}=-14\sqrt{2}\)
b: \(\left(\dfrac{x-\sqrt{x}}{\sqrt{x}-1}-2\right)\cdot\left(\dfrac{x+\sqrt{x}}{\sqrt{x}+1}+2\right)\)
\(=\left(\dfrac{\sqrt{x}\left(\sqrt{x}-1\right)}{\sqrt{x}-1}-2\right)\left(\dfrac{\sqrt{x}\left(\sqrt{x}+1\right)}{\sqrt{x}+1}+2\right)\)
\(=\left(\sqrt{x}-2\right)\left(\sqrt{x}+2\right)=x-4\)
Đúng 1
Bình luận (0)
