In deriving the Lorentz transformation equations, we started by considering an event (a flash) that occurred at some time tB and at the location xB = 0, i.e., the location of Bob’s spaceship (with Bob moving to the right at velocity v from the perspective of Alice). We then wrote down the invariant interval equation for this situation. What form did this equation take (where the A and B subscripts represent Alice’s and Bob’s coordinates, respectively)?