Question 304084: Give a counterexample: the square of a number added to the sum of twice the number and 8 is a prime number. Answer by vleith(2983) (Show Source):
You can put this solution on YOUR website! Pick any even number.
Squaring it results in a number that has a factor of 2.
Doubling it and adding 8 also results in a number that has a factor of 2.
So the resulting sum will always have a factor of 2 as well.
And thus cannot be prime.
So pick 2 or 4 or any even number.
And you will have your counter example
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