Respuesta :

Panoyin
The constant that is to form a perfect square trinomial is 9.

x² - 6x + 9
x² - 3x - 3x + 9
x(x) - x(3) - 3(x) + 3(3)
x(x - 3) - 3(x - 3)
(x - 3)(x - 3)
(x - 3)²