Identifying key ideas what are the five principles of government expressed in the constitution?

1)  Popular Sovereignty —
  The idea that the government's authority comes from the people ;

2) Limited Government —
The government is limited in the way they can act by the Constitution.
Restricts Government power. {restriction of government power} ;

3) Separation of Powers —
The division of power among the legislative, executive, and judicial branches of government to ensure that there's no concentration and abuse of power. {separate jobs of the branches of government} ; 

4) Checks and Balances  — Allows branches of government to restrain each others' powers ;

5) Federalism — the division of power between the national and state governments.

Complementary goods. they go together, thats why one price increase and the others demand increases