One of the fundamental themes of calculus is to find the slope of the tangent to a curve at a point. To see how this can be done , consider the point (2,4) on the graph of ( see figure below)
(a) Find the slope of the line joining (2,4) and (3,9). Is the slope of the tangent line at (2,4) greater than or less than this number?
(b) find the slope of the line joining (2,4) and (1,1). Is the slope of tangent line greater than or less than this number?