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Marek earned this badge 2 times
sep 12 '11 at 21:31
Why does this expression equal $\pi$?
jul 21 '11 at 10:09
Solving for the implicit function $f\left(f(x)y+\frac{x}{y}\right)=xyf\left(x^2+y^2\right)$ and $f(1)=1$

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