Completion requirements

The figure shows a set of Cartesian axes labelled x and y concentrated mainly in the upper-right quadrant. The graph of y equals f of x is shown and it passes through the origin from the lower-left quadrant and has two local maximum points and one local minimum. There are points a and b marked on the positive x-axis and joined by a bold line with the point a nearer the origin. Vertical lines join the points a and b to the curve and the area between the graph and the positive x-axis is shaded.