Science, Maths & Technology
Introduction to complex analysis
...becomes a tangent to the graph of f at a point left parenthesis c comma f of c right parenthesis , where c lies somewhere between a and x . Clearly, the gradient of the original chord must be equal to the gradient of the tangent, so f of x minus f of a divided by x minus a equals f super prime of c full stop Multiplication by x minus a gives f of x equals f of a plus left...