Question 62210
20. Identify the axis of symmetry, create a suitable table of values, then sketch the graph (including the axis of symmetry). 
y=x^2-4x 
COMPLETE THE SQUARE USING ALL X TERMS USING (A-B)^2=A^2-2AB+B^2..BY FINDING B AND THEN BY ADDING AND SUBTRACTING B^2
HERE A=X...-4X=-2XB...B=2.....SO ADD AND SUBTRACT 2^2 TO COMPLETE THE SQUARE 
Y=[(X)^2-2(X)*2+2^2]-2^2=(X-2)^2-4
HENCE AXIS OF SYMMETRY IS X-2=0...OR...X=2
GIVE DIFFERENT VALUES FOR X AND FIND Y ..FOR EX..IF X =0...Y=0^2-4*0=0
X......0........2.......4........6..........-2.........-4....ETC...
Y=.....0.......-4.......0........12...........12.........32.....ETC
GRAPH WILL LOOK LIKE THIS 

{{{ graph( 500, 500, -10, 10, -50, 50,x^2-4*x) }}}