giúp em với ạ camon nhiềuuuu

`a, A = \sqrt{(4 - \sqrt{15})^2} + \sqrt{15}`

`=> A = |4 - \sqrt{15}| + \sqrt{15}`

`=> A = 4 -\sqrt{15} + \sqrt{15}`

`=> A = 4`

Vậy `A =4`

`b, B = \sqrt{(2 - \sqrt{3})^2} + \sqrt{(1 - \sqrt{3})^2}`

`=> B = |2 - \sqrt{3}| + |1 - \sqrt{3}|`

`=> B = 2 - \sqrt{3} + \sqrt{3} - 1`

`=> B =1`

Vậy `B = 1`

`c, C = \sqrt{49 - 12\sqrt{5}} - \sqrt{49 + 12\sqrt{5}}`

`=> C = \sqrt{49 - 2.2.3\sqrt{5}} - \sqrt{49 + 2.2.3\sqrt{5}}`

`=> C = \sqrt{4 - 2.2\sqrt{45} + 45} - \sqrt{4 + 2.2\sqrt{45} + 45}`

`=> C = \sqrt{(2 - \sqrt{45})^2} - \sqrt{(2+  \sqrt{45})^2}`

`=> C = |2 - \sqrt{45}| - |2 + \sqrt{45}|`

`=> C= \sqrt{45} - 2 - 2 - \sqrt{45}`

`=> C =-4`

Vậy `C = -4`

`d, D = \sqrt{29 + 12\sqrt{5}} - \sqrt{29 - 12\sqrt{5}}`

`=> D= \sqrt{29 + 2.3.2\sqrt{5}} - \sqrt{29 - 2.3.2\sqrt{5}}`

`=> D = \sqrt{9 + 2.3\sqrt{20} + 20} - \sqrt{9 - 2.3\sqrt{20} + 20}`

`=> D=  \sqrt{(3 + \sqrt{20})^2} - \sqrt{(3 - \sqrt{20})^2}`

`=> D= |3 + \sqrt{20}| - |3 - \sqrt{20}|`

`=> D = 3 +\sqrt{20} - (\sqrt{20} - 3)`

`=> D = 3 + \sqrt{20} - \sqrt{20} + 3`

`=> D = 6`

Vậy `D=  6`

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