Let $x, y, z$ be real numbers such that $x+y+z=-2$ and
\[
(x^2+xy+y^2)(y^2+yz+z^2) + (y^2+yz+z^2)(z^2+zx+x^2) + (z^2+zx+x^2)(x^2+xy+y^2) = 625+ \frac{3}{4}(xy+yz+zx)^2.
\]
Compute $|xy+yz+zx|$.

Let's think step by step and output the final answer within \boxed{}.
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