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If x is a positive integer, is x! + (x + 1) a prime number?

(1) x < 10 (2) x is even

Could be B.

if x = 2, x! + (x + 1) = 5 prime
if x = 4, x! + (x + 1) = 29 prime
if x = 6, x! + (x + 1) = 727? probably prime
if x = 8, x! + (x + 1) = 40329? probably prime
if x = 10, x! + (x + 1) = 3628811? probably prime

If x is a positive integer, is x! + (x + 1) a prime number?

(1) x < 10 (2) x is even

Quote:

get C

Stmt1 x <10> x can be 2 so 2!+3 = 5 - prime But x can be 3 so 3!+4 = 10 - Non prime So InSuff

Stmt2 x is even.

x can be 2 so 2!+3 = 5 - prime But x can be 14 so 14! + 15 is not prime

Combine 1 and 2 you will see x! + x + 1 is prime

I agree with everyone who said E. As was noted upthread, if you combine the 2 statments, you are left with 2, 4, 6, 8 as possibilities for x. However, after Himalayan did the math, it was noted that using x=8 does not produce a prime number.

I couldn’t help myself but stay impressed. young leader who can now basically speak Chinese and handle things alone (I’m Korean Canadian by the way, so...