Simple...
you have: Which value must be added to the expression

to make it a perfect-square trinomial?

(Answer)
A perfect square is a whole number that is the square of an integer..-->>>
EX: 16 is a perfect square because 4*4=16

-->>(No)
This expression can't be factored with rational numbers, nor is the polynomial factorable with rational numbers.

-->>(No)
This expression can't be factored with rational numbers, nor is the polynomial factorable with rational numbers.

-->>(No)
This expression can't be factored with rational numbers, nor is the polynomial factorable with rational numbers.
Thus, your answer.