Suppose that $f : [a, b] \to \R$ is so that $\abs{f(t)} \leq M$ for all $t \in [a, b]$. Then $-M \leq L(f)$ and $U(f) \leq M$.
Suppose $f : \R \to \R$ is integrable on every compact interval, and define \[ F(t) = \int_0^t f(x)\,dx.\] If we wish to show that $F$ is continuous at $x_0$, which of the following quantities must we be able to force to be small?
Suppose $f : [0, 1] \to \R$ has the property that for every open subset of $[0, 1]$ contains a point at which $f$ is zero. Which of the following is true?