This takes some common sense.  For instance, for , we’d expect the graph to pass through the origin, and as it heads to the right get higher and higher, at a faster and faster rate.  Also, as you head to the left of the y-axis, you’d expect it to get higher and higher as well:

 however is a little bit different.  Going right from the x-axis, we’d expect the line to get higher and higher and the slope to get steeper and steeper.  However, in the negative x region, the line’s actually going to be below the x-axis, because when you cube a negative number the negative sign stays there in your answer.  So going to the left of the y-axis, the line’s going to get more and more negative and the slope’s going to get steeper and steeper: