Could you please elaborate on the concept of USDX futures? I'm curious to understand how they work and what role they play in the financial markets. Specifically, I'd like to know: what is the USDX index and how does it relate to the futures contracts? What are the key factors that influence the price of USDX futures? How do investors use USDX futures to hedge their portfolios or speculate on currency movements? Additionally, could you provide an example of a trading strategy involving USDX futures? Your insights would be greatly appreciated.