\(=\dfrac{\left(\sqrt{a}-\sqrt{b}\right)\left(\sqrt{a}+\sqrt{b}\right)}{\sqrt{a}-\sqrt{b}}-\dfrac{\left(\sqrt{a}-\sqrt{b}\right)\left(a+\sqrt{ab}+b\right)}{\left(\sqrt{a}-\sqrt{b}\right)\left(\sqrt{a}+\sqrt{b}\right)}\\ =\sqrt{a}+\sqrt{b}-\dfrac{a+\sqrt{ab}+b}{\sqrt{a}+\sqrt{b}}\\ =\dfrac{\left(\sqrt{a}+\sqrt{b}\right)^2-a-\sqrt{ab}-b}{\sqrt{a}+\sqrt{b}}\\ =\dfrac{a+2\sqrt{ab}+b-a-\sqrt{ab}-b}{\sqrt{a}+\sqrt{b}}=\dfrac{\sqrt{ab}}{\sqrt{a}+\sqrt{b}}\)
rút gọn biểu thức sau với a≥0; b≥0; a≠b