B.5.QD:4.4 - Work a case that reveals the difficulty

Choose a small case that exercises the changed condition or new operation. Attempt the requested construction or inference and explain where it succeeds or stops.

Use the result to improve the question. A successful case can expose a reusable relation. A failed case can identify a missing premise, an incompatible demand or an operation still to be developed. If two admissible cases give different answers from the same supplied information, ask for the missing distinction or a result valid for both.

A case establishes its own result. A broader mathematical claim needs its derivation, and applying a physical model needs the relevant physical basis. The question can already be useful before those answers are established: the first attempt should make the next contribution more identifiable.

Begin with available reasoning and information. Obtain further evidence only when its possible answers can change the useful inquiry enough to justify the effort under C.11.DUA. An existing bound or conditional answer may settle the current use.