Answer: For the GCF one, the GCF would be 
 because you are factoring from both 
 and 
, the reason it cannot be 
 is because that exponent value exceeds the exponent value of 
.
Explanation:
So when you find a greatest common factor (GCF) you are basically trying to simplify the expression by extracting numbers to put it into its simplest form. The GCF of 15 and 12, is 3. And the GCF of the exponents would be 
 .