Let \( P \) be the image of the point \( Q(7,-2,5) \) in the line \( L:\; \dfrac{x-1}{2} = \dfrac{y+1}{3} = \dfrac{z}{4} \) and \( R(5,p,q) \) be a point on \( L \). Then the square of the area of \( \triangle PQR \) is \( \underline{\phantom{xxxx}} \).
