Find the number to add to x^2-16x to make it a perfect square trinomial. Write that trinomial as the square of a binomial.
To find the number to add to x^2 - 16x to make it a perfect square trinomial, we want to take half of the coefficient of the x term (-16) and square it.
Half of -16 is -8, and (-8)^2 = 64.
So, the trinomial that is the square of a binomial is:
(x - 8)^2