Plotting the values for the cube of x introduces a notion that proves essential to working with the graphs of exponents. As Figure 10.16 illustrates, in situations where the exponent for the number is even, you see graphs that open upward. Such graphs are symmetrical with respect to the y axis.
In contrast, in situations where the exponent of the variable is odd, then only one arm of the graph extends upward. As Figure 10.17 shows, the graph that results is symmetrical with respect to the origin of the Cartesian coordinate plane.