Question 135321
Determine the constant that should be added to the binomial so that it becomes a perfect
square trinomial. Then write and factor the trinomial.
x²-4 
--------------
A perfect square trinomial cannot have -4 as it's 3rd term because it
is the square of (1/2)the coefficient of the 2nd term.  Since it is
a square, it cannot be negative.
========================
Cheers,
Stan H.