Answer:
Step-by-step explanation:
You can use KI and K4[Fe(CN)6].
When you add KI in a solution with only Cu2+ nothing will happen, but when you add K4[Fe(CN)6] it will form a solid of Cu2[Fe(CN)6] that will be reddish-brown.
When you add K4[Fe(CN)6] in a solution with only Bi3+ nothing will happen, but when you add KI it will form a solid of BiI3 that will be black.
So in a solution which contains both of then, you can add KI to determinate Bi3+, if you see a black solid. If nothing happens, you can affirme that it contains Cu2+.