Try several graphs of
on the same axes. (i.e., use different values of a)
I have graphed five equations on the following graph. These include
a = 1, 2, 3, 4, 10
The larger the value of a, the thinner the parabola.
When a is negative, the vertex remains the same and the resulting graph is a reflection over the x-axis. The five equations graphed below are:
a = -1, -2, -3, -4, -10