Coordinate Geometry: JEE Main 2026 Mathematics question

Let the line $x-y=4$ intersect the circle C : $(x-4)^2+(y+3)^2=9$ at the points Q and R. If P$(\alpha,\beta)$ is a point on C such that PQ $=$ PR, then $(6\alpha+8\beta)^2$ is equal to ______.