Let a line passing through the point \( (-1, 2, 3) \) intersects the lines \( L_1 : \dfrac{x-1}{3}=\dfrac{y-2}{2}=\dfrac{z+1}{-2} \) at \( M(\alpha,\beta,\gamma) \) and \( L_2 : \dfrac{x+2}{-3}=\dfrac{y-2}{-2}=\dfrac{z-1}{4} \) at \( N(a,b,c) \). Then, the value of \( \dfrac{(\alpha+\beta+\gamma)^2}{(a+b+c)^2} \) equals _______.
