Functions - Is the Relation a Function?

Video: https://www.youtube.com/watch?v=VfMcgQVUGMk

Video: https://www.youtube.com/watch?v=OxZ0JL4Bjzk

Is this Relation a Function: https://www.youtube.com/watch?v=q3OlT3hPIGU

Function Tables: https://www.youtube.com/watch?v=M0ipRw4SWhA

Video Click This Video to learn how to write D/R

Is it a function: http://teachers.henrico.k12.va.us/math/hcpsalgebra1/Documents/examviewweb/ev5-5.htm

Function Quiz: http://www.phschool.com/webcodes10/index.cfm?fuseaction=home.gotoWebCode&wcprefix=ata&wcsuffix=0502