Answer: Â Take it one step at a time. The chart should have x values close to 0, both positive and negative. You get the y-values by substituting for x and working out the calculation.
Step-by-step explanation:
chart for y = -x²   Remember you are squaring the (x) then multiply × -1 so all y-values are negative numbers.
x   |   y Â
-2 Â Â -4
-1 Â Â Â -1
0 Â Â 0
 1    -1
 2   - 4
Plot those points on the graph, draw the parabola. It should look like the first graph attached. Since the vertex of the parabola is at the top, it is a maximum.
The parabola is a mirror image on either side of the y-axis, so that is the line of symmetry
Chart for y = x² –4 . figure x² first, then subtract 4
 x . | . y Â
-2 Â Â 0 . Â Â Â +4-2=0
 -1   -3    +1 - 4 = -3
 0   -4
 1   -3
 2   0
 3   1    9 - 4 = 5
Your graph should look like the second (green) attached graph
I hope this is enough help for now.