What is the formula for cutting LVLs that are flush to ceiling but need to be cut on top for the roof slope sitting on A 2x4 wall?

We do not cut beams since any cutting weakens a beam. For example, you need a 4x12 lvl and you do what you are planning, taking a slope off the end so its only 6" high. Well you now have effectively created a 4x6 beam no longer able to carry what a 4x12 beam could carry. We sit our roofs above the top edge of the beam. Are you going to be inspected?

Yes we are being inspected.

Ask the inspector your question and see what he thinks. We follow the 2006 IBC and can not notch or cut beams.