Let F(x)=∫axf(t)dt, where f is continuous on the closed interval [a,b]. Answer the following:
(i) State the First Fundamental Theorem of Calculus.
(ii) Explain, with reasons, how the sign of f(x) on an interval (p,q)⊂(a,b) determines whether F(x) is increasing or decreasing on that interval.
(iii) Suppose f(x)≥0 for 1<x<4 and f(x)≤0 for 4<x<6, with f continuous on [1,6]. Describe the behaviour of F(x)=∫1xf(t)dt on (1,4) and on (4,6), and comment on the nature of the point x=4 for the function F. Justify your answer.