Question
The positive square root of $7+\sqrt{48},$ is:

Answer

  1. $2+\sqrt3$
    Solution:
    $\sqrt{7+\sqrt{48}}$
    $=\sqrt{7+2\sqrt{12}}$
    $=\sqrt{4+3+2\sqrt4\times\sqrt3}$
    $=\sqrt{\big(\sqrt4\big)^2+\big(\sqrt3\big)^2+2\times\sqrt4\times\sqrt3}$
    $=\sqrt{\big(\sqrt4+\sqrt3\big)^2}$
    $=\pm\big(\sqrt4+\sqrt3\big)$
    Positive value is $\sqrt4+\sqrt3=2+\sqrt3$
    Hence, correct option is (c).

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