Why did the founding fathers compromise on using a federal system for the new government

The Founding Fathers compromised on using a federal system for the new government because a federal system would create a system of power sharing between the national and state governments. There was great debate about state v. federal power in the writing of the constitution and the choice of a federal system was a compromise which sought to implement and protect the concerns of creating a tyrannical federal government but also one that could provide for the people with a strong national government. 

Y=-121/7+11/7x i think this may be wrong