# Another surd

Algebra Level 3

$\large \sqrt{11 + \sqrt{21}}$

The above expression can be expressed as $$\sqrt{\dfrac{a}{b}} + \sqrt{\dfrac{c}{d}}$$, where $$a,b,c$$ and $$d$$ are positive integers with $$\gcd(a,b) = \gcd(c,d) = 1$$. Find $$a+b+c+d$$.

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