If $x = {{\sqrt 5 + \sqrt 2 } \over {\sqrt 5 - \sqrt 2 }},y = {{\sqrt 5 - \sqrt 2 } \over {\sqrt 5 + \sqrt 2 }},$ then $3{x^2} + 4xy - 3{y^2} = $

  • A

    ${1 \over 3}[56\sqrt {10} - 12]$

  • B

    ${1 \over 3}[56\sqrt {10} + 12]$

  • C

    ${1 \over 3}[56 + 12\sqrt {10} ]$

  • D

    None of these

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