If we take a look at the graphs below, the red curve represents the graph of , and the dark green curve represents the graph of . The purple region falls below the red curve is bounded between x = h and 1, while the blue region is bounded between x = 1 and k.
Now scroll the value of k, do you notice that point K moves according to the k value? The y-coordinate of point K is the area of the blue region. Same concept applies to the value of h and point H. Here comes the question, do you know how to get negative y-coordinate for point H?
Betty, Created with GeoGebra