Remember, we are graphing the equation with different a-values. Observe that when we substitute zero in for x, the a-value has no effect on the graph.
By substituting x=0 we get a*0*0+0+2=y.
This simplifies to 2=y, which is where we get the y-coordinate for the common point of (0,2).
If we substituted any other number in for x the a-value would affect the y-coordinate. Therefore, the point of any other x-value would not be common to all graphs of the form .
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