Question

complete the square to make the binomial x^2-8x a perfect trinomial

Answer 1

The general Formula looks like this:
$x^2 +bx + ( \frac{b}{2})^2$
This really only involves 2 steps:
1) Take half of "x" coefficient. ----> -8/2 = -4
2) Square that number.   ---------->  (-4)^2 = 16

Perfect trinomial for this example is then:
$x^2 -8x+16$