prime number

kanha81 wrote:q: If x is a prime number greater than 2, which of following is a prime number?
a) x^2
b) x/2
c) 3x
d) x-4
e) x^2+1

Not sure there is an answer to this that is always true.

a) If a prime number is squared it is divisible by itself so it's no longer prime
b) A prime number > 2 divided by 2 leaves a fraction which isn't a prime number.
c) any prime number multipled by 3 can also be divided by 3 making it not a prime number
d) 29 is prime 29-4 is 25 (not prime)
e)5^2 = 25. 25 + 1 = 26 (not prime)

kanha81 wrote:q: If x is a prime number greater than 2, which of following is a prime number?
a) x^2
b) x/2
c) 3x
d) x-4
e) x^2+1

IMO D

x=7

kanha81 wrote:q: If x is a prime number greater than 2, which of following is a prime number?
a) x^2
b) x/2
c) 3x
d) x-4
e) x^2+1

incorrect question i guess!

Incorrect question....

D is wrong if x= 19, x-4=15, not prime

kanha81 wrote:q: If x is a prime number greater than 2, which of following is a prime number?
a) x^2
b) x/2
c) 3x
d) x-4
e) x^2+1

I guess, question has to be "which of following could be a prime numbre?" In that case, D will be the answer.