3 is a factor of both 3 and 9. 1 is the other common factor. 3 is the greatest common factor. If you were looking at larger numbers with many common factors like 24 and 48, factors include 1,2,3,4,6,8,12,&24 You might find other smaller factors useful, but most of the time it's the gif that needs to be factored out: 3(x^2 + 3)
