Question

The graph of this quadratic function is a parabola. What is the x-coordinate of the vertex?
y=x^2-8x+16

Answer 1

use the formula x=-b/(2a) to find the x-coordinate of the vertex.

Answer 2

or just do the first derivative..you get y'=2x-8 and set it to be zero (it means that you're looking for a point where the slope of the tangent line is zero)...you get x=4 and that's the x coordinate of the vertex, and if you plug that value into the equation of parabola you'll get the y coordinate