When you make a table from a graph you are really just listing the coordinates of a few points that lie on the parabola. Remember that there are an infinite number of points on the graph, but you are only going to list a few, usually the critical attributes.
It is common for a table to be organized by increasing values of x. So, the same table might look like this.
x |
y |
-4 |
0 |
-3 |
-5 |
-2 |
-8 |
-1 |
-9 |
0 |
-8 |
1 |
-5 |
2 |
0 |
The axis of symmetry is x = -1 because it is a vertical line and MUST pass through the vertex point of (-1, -9).
The symmetry of the parabola across x = -1 is easier to view if the table is horizontal.
x |
-4 |
-3 |
-2 |
-1 |
0 |
1 |
2 |
y |
0 |
-5 |
-8 |
-9 |
-8 |
-5 |
0 |
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