4. If | f | is a Riemann integrable function on the interval [0, 1], then f is integrable on [0, 1]. (A)O(B)X

6. We already know that the series is convergent. Now, rewrite the series by combining 2n consecutively positive terms in the series, then followed by 2n consecutively negative terms, where n = 1, 2, 3, …, to get a new series as follows:+... , then the new series is still convergent. (A)O(B)X