Which of the following is a prime number?
A. 121
B. 287
C. 445
D. 571

answer:

D. (and.. a thank you would be nice :} )

Step-by-step explanation:

For 121 to be a prime number, it would have been required that 121 has only two divisors, i.e., itself and 1. However, 121 is a semiprime (also called biprime or 2-almost-prime), because it is the product of a two non-necessarily distinct prime numbers. Indeed, 121 = 11 x 11, where 11 is a prime number. So no it 121 is not a prime number. For 287 to be a prime number, it would have been required that 287 has only two divisors, i.e., itself and 1. However, 287 is a semiprime (also called biprime or 2-almost-prime), because it is the product of a two non-necessarily distinct prime numbers. Indeed, 287 = 7 x 41, where 7 and 41 are both prime numbers. So no it is not a prime number.  For 445 to be a prime number, it would have been required that 445 has only two divisors, i.e., itself and 1. However, 445 is a semiprime (also called biprime or 2-almost-prime), because it is the product of a two non-necessarily distinct prime numbers. Indeed, 445 = 5 x 89, where 5 and 89 are both prime numbers so no it is not a prime number. BUT For 571, the answer is: yes, 571 is a prime number because it has only two distinct divisors: 1 and itself (571).

answer: -2+√x,-2-√x

i hope this , i don't know if you're looking for a pair or not.