\[\boxed{\mathbf{461}.}\]
\[1)\ \frac{\sqrt{a} - \sqrt{b}}{\sqrt[4]{a} - \sqrt[4]{b}} - \frac{\sqrt{a} + \sqrt[4]{\text{ab}}}{\sqrt[4]{a} + \sqrt[4]{b}} =\]
\[= \frac{\left( \sqrt[4]{a} \right)^{2} - \left( \sqrt[4]{b} \right)^{2}}{\sqrt[4]{a} - \sqrt[4]{b}} -\]
\[- \frac{\left( \sqrt[4]{a} \right)^{2} + \sqrt[4]{a} \bullet \sqrt[4]{b}}{\sqrt[4]{a} + \sqrt[4]{b}} =\]
\[= \frac{\left( \sqrt[4]{a} - \sqrt[4]{b} \right)\left( \sqrt[4]{a} + \sqrt[4]{b} \right)}{\sqrt[4]{a} - \sqrt[4]{b}} -\]
\[- \frac{\sqrt[4]{a} \bullet \left( \sqrt[4]{a} + \sqrt[4]{b} \right)}{\sqrt[4]{a} + \sqrt[4]{b}} = \sqrt[4]{a} +\]
\[+ \sqrt[4]{b} - \sqrt[4]{a} = \sqrt[4]{b};\]
\[2)\ \frac{a - b}{\sqrt[3]{a} - \sqrt[3]{b}} - \frac{a + b}{\sqrt[3]{a} + \sqrt[3]{b}} =\]
\[= \frac{\left( \sqrt[3]{a} \right)^{3} - \left( \sqrt[3]{b} \right)^{3}}{\sqrt[3]{a} - \sqrt[3]{b}} -\]
\[- \frac{\left( \sqrt[3]{a} \right)^{3} + \left( \sqrt[3]{b} \right)^{3}}{\sqrt[3]{a} + \sqrt[3]{b}} =\]
\[= \frac{\left( \sqrt[3]{a} - \sqrt[3]{b} \right)\left( \sqrt[3]{a^{2}} + \sqrt[3]{\text{ab}} + \sqrt[3]{b^{2}} \right)}{\sqrt[3]{a} - \sqrt[3]{b}} -\]
\[- \frac{\left( \sqrt[3]{a} + \sqrt[3]{b} \right)\left( \sqrt[3]{a^{2}} - \sqrt[3]{\text{ab}} + \sqrt[3]{b^{2}} \right)}{\sqrt[3]{a} + \sqrt[3]{b}} =\]
\[= \left( \sqrt[3]{a^{2}} + \sqrt[3]{\text{ab}} + \sqrt[3]{b^{2}} \right) -\]
\[- \left( \sqrt[3]{a^{2}} - \sqrt[3]{\text{ab}} + \sqrt[3]{b^{2}} \right) = 2\sqrt[3]{\text{ab}};\]
\[3)\ \left( \frac{a + b}{\sqrt[3]{a} + \sqrt[3]{b}} - \sqrt[3]{\text{ab}} \right)\ :\]
\[:\left( \sqrt[3]{a} - \sqrt[3]{b} \right)^{2} =\]
\[= \left( \frac{\left( \sqrt[3]{a} \right)^{3} + \left( \sqrt[3]{b} \right)^{3}}{\sqrt[3]{a} + \sqrt[3]{b}} - \sqrt[3]{\text{ab}} \right)\ :\]
\[:\left( \sqrt[3]{a} - \sqrt[3]{b} \right)^{2} =\]