a,
`\sqrt{3-2\sqrt{2}}=\sqrt{2-2\sqrt{2}+1}=\sqrt{(\sqrt{2}-1)^2}=\sqrt{2}-1`
b,
`\sqrt{5+2\sqrt{6}}=\sqrt{2+2\sqrt6+3}=\sqrt{(\sqrt2+\sqrt3)^2}=\sqrt2+\sqrt3`
c,
`\sqrt{8-2\sqrt{15}}=\sqrt{5-2\sqrt{15}+3}=\sqrt{(\sqrt5-\sqrt3)^2}=\sqrt5-\sqrt3`
d,
`\sqrt{7+4\sqrt{3}}=\sqrt{4+2\sqrt{12}+3}=\sqrt{(2+\sqrt3)^2}=2+\sqrt3`