What are the challenges of empire, what is the usual result? or put into math terms: ?

Diverse + Multiethnic = Hard to Unify
Empires generally covered large expansive territories across the world, these incorporated many diverse countries, and cultures under oppressive rules. Empires were often formed to demonstrate power and force of a nation often at the expense of citizens there. Due to the diversity and multi-ethnic nature of these territories, they were hard to unify and generally broke up due to the fact of being formed under duress.

How  did spanish  power increaseunder charles  v and philip ii? in 1519,charles  v inherited a huge empire. he became king of  spain  and was also the heir to the hapsburg empire. during his 42-year reign, philip worked to expand  spanish  influence, strengthen the catholic church, and make his own power absolute. hope this !