“…In Section 3, using the property of a unimodal function ϕ(x), which is introduced in Section 2, some sufficient conditions for Lemma 2.6 are established. Moreover, we introduce Theorem 3.6, which extends the previous results in [9,20]. Using the previous results given in [19], we finally prove Theorem 1.1 in the last part of Section 3.…”