Question 43569
Identify the axis of symmetry, creat a suitable table of values, the sketch the graph (including the axis of symmetry). 
y = x^2-4x

Put in vertex form by completing the square:

y+4=x^2-4x+4
y+4=(x-2)^2

Vertex is at (2,-4)
So, axiis of symmetry is the line x-2.
Sketch the graph:
*[invoke quadratic "x",1,-4,0]
Cheers,
Stan H.