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is a2-4 prime

Guest Feb 25, 2017
 #1
avatar+26750 
+5

"is a2-4 prime"

 

Depends on the value of a.  

 

If a = 3, then a2 - 4 = 5, which is prime.  

 

If a = 4 then a2 - 4 = 12, which is not prime.

.

Alan  Feb 25, 2017
 #2
avatar+7002 
0

Is a^2 - 4 prime?

 

If a is an integer > 3, it will be prime. Because if the least value to make it not prime = y, then

 

y - 2 > 1, because we can't let y-2 = 1.

y > 3.

 

If a is an integer < 3 it will be either prime or negative.

MaxWong  Feb 25, 2017

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