Suppose `f` is any continuous function on the interval `[a,b]`. Explain why `int_a^b ftext[(]t text[)] dt=Ftext[(]b text[)]`, where `Ftext[(]t text[)]` is the solution of the initial value problem
`(dF)/(dt)=ftext[(]t text[)]`, `Ftext[(]a text[)]=0`.