Algebra/Graphing Polynomials

The graph of an equation represents all the points for which that equation are valid. The points where the different graphs intersect show the points that are valid for more than one equation in a system.

For instance figure 1 shows a graph for the parabola $y=-x^{2}+9$.

Figure 1

Table for various values of x and y

x	y	x	y
-4	-7	4	-7
-3	0	3	0
-2	5	2	5
0	9