There are two neighboring points P and Q on the curve f(x)=x^2
(a) Determine m(h), the slope of the straight line PQ
(b) The slope, S, of the tangent at P is defined as S=lim h->0 m(h). Find the value of S.
(c) Use this value of S to show that the equation of the tangent at P is y=4x-4.