已知\(\overrightarrow{a}{=}(m{,}1)\),\(\overrightarrow{b}{=}(4{-}n{,}2)\),\(m{ > }0\),\(n{ > }0\),若\(\overrightarrow{a}{/\!/}\overrightarrow{b}\),则\(\dfrac{1}{m}{+}\dfrac{8}{n}\)的最小值______ .
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