Let a smooth curve \( y=f(x) \) be such that the slope of the tangent at any point \( (x,y) \) on it is directly proportional to \( \left( \dfrac{-y}{x} \right) \). If the curve passes through the points \( (1,2) \) and \( (8,1) \) then \( \left| y\left(\dfrac{1}{8}\right) \right| \) is equal to:
