#1) The GCF is x. #2) The GCF is 11. #3) The GCF is 8x.
For #1, the only thing each term has in common is an x. This makes it the GCF. For #2, both terms are divisible by 11. Neither of them have a variable, so the GCF does not include x. 11 is the GCF. For #3, all of the terms are divisible by 8. Additionally, they all have an x. This makes the GCF 8x.