(A) Given that P = {X0, X1, X2.......Xn} is an arbitrary partition of [a,b], find the lower and upper sum for f(x)=x+3.
(B) Use your answers to part (a) to evaluate the integral of f(x) from a to b.
(B) Use your answers to part (a) to evaluate the integral of f(x) from a to b.