Suppose you added an entry to the timeline in Question 16 to describe what the Aztecs were doing before the first entry on the timeline. Your entry might read:

in the 1800s, locomotives powered by steam made transportation faster and cheaper. the resulting rapid growth of railroads led to the connection of the atlantic and pacific railroad in oklahoma city in 1897.

in the last years of the century, the improvement of steam-based engines the expansion and growth of railroads. this growth increased when the companies started to build and expand, such as the atlantic and pacific railroad, which connected new mexico with california, and missouri with oklahoma. many of these new networks were built in oklahoma, and these changes transportation henceforward.

1) the degree of the function is odd, so the ends of the graph continue in opposite directions. because the leading coefficient is positive, the left side of the graph continues down the coordinate plane and the right side continues upward.