Answer:
Deductive reasoning
Explanation:
Given : John concludes that, since (x-5) is a factor of the polynomial 
 , if he performed the long division
, if he performed the long division 
 , the remainder would be zero.
, the remainder would be zero. 
To find : This is an example of ___________ reasoning 
 ?
?
Solution : 
The above situation make conclusion when we know the fact that (x-5)
is the factor as the factor of polynomial divide it completely.
Therefore, This is the example of deductive reasoning. 
Deductive reasoning is the process by which a person makes conclusions based on previously known facts.