Game Development Reference
In-Depth Information
with the positive value of the y-intercept, causes the graph to cross the y axis
above the x axis.
You see the second, lower graph in Figure 10.29. The lower graph crosses the
y axis 4 units below the x axis. To create the equation that generates this graph,
use the following steps:
1. Click the menu item for Value. Then click in the lower equation compo-
sition area to position Value field. Type x in the Value field.
2. Click the Power menu item. To position the Exponent field, click to the
upper right of the value. After you position the Exponent field, type 3
in it.
3. Click the Subtract menu item. Then click to the right of the Value field to
position the minus sign.
4. Now click Value in the menu. To position the Value field, click after the
minus sign. Type 4 four in the field. This value lowers the vertex of the
parabola 4 units below the x axis.
5. To generate the graph, locate the lower-right panel of Visual Formula and
click the Chart for Formula 2 button. As Figure 10.29 illustrates, a second
graph appears, lower than the first.
Translating Absolute Values
As previous exercises emphasized, when you plot the solutions to an equation that
contains an absolute value, the graph that results is symmetrical with respect to
the y axis, and you can shift equations containing absolute values along the y axis.
Shifting involves changing the value of the y-intercept. Figure 10.30 illustrates
shifting using positive and negative y-intercept values. One graph moves the
y-intercept up to 6. The other moves it down to 6.
To use Visual Formula to graph the solutions of equations that shift the graphs of
absolute values, follow these steps (refer to Figure 10.31):
1. For an equation that reads y ¼jxjþb , work in the top equation compo-
sition area. First, click the Abs menu item. Then click in the equation
composition area to position the absolute value bars.
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