`a)``\sqrt{5+2\sqrt{6}}-\sqrt{5-2\sqrt{6}}`
`=\sqrt{2+2\sqrt{6}+3}-\sqrt{2-2\sqrt{6}-3}`
`=``\sqrt{(\sqrt{2}+\sqrt{3})^{2}}-\sqrt{(\sqrt{2}-\sqrt{3})^{2}}`
`=``|\sqrt{2}+\sqrt{3}|-|\sqrt{2}-\sqrt{3}|`
`=``\sqrt{2}+\sqrt{3}-\sqrt{3}+\sqrt{2}`
`=``2\sqrt{2}`
`c)``\sqrt{4-2\sqrt{3}}+\sqrt{4+2\sqrt{3}}`
`=``\sqrt{1-2\sqrt{3}+3}+\sqrt{1+2\sqrt{3}+3}`
`=``\sqrt{(1-\sqrt{3})^{2}}+\sqrt{(1+\sqrt{3})^{2}}`
`=``|1-\sqrt{3}|+|1+\sqrt{3}|`
`=``\sqrt{3}-1+1+\sqrt{3}`
`=``2\sqrt{3}`
