vertex and axis of symmetry

Question

identify vertex, axis of symmetry and min/max of f(x)=x2-4x+8

Answer 1

If y = Ax² + Bx + C, then the x-coordinate of the vertex is -B/(2A) and the axis of symmetry is the vertical line x = -B/(2A).

 

So, for f(x) = x² - 4x + 8, x-coordinate of vertex = -(-4)/(2(1)) = 2

 

                                    vertex = (2, f(2)) = (2, 4)

 

                                    axis of symmetry:  x = 2