q-Supercongruences from Jackson's 8Φ7 summation and Watson's 8Φ7 transformation

q-Supercongruences modulo the fifth and sixth powers of a cyclotomic polynomial are very rare in the literature. In this paper, we establish some q-supercongruences modulo the fifth and sixth powers of a cyclotomic polynomial in terms of Jackson's (8)phi(7) summation, Watson's (8)phi(7) transformation, the creative microscoping method recently introduced by Guo and Zudilin, and the Chinese remainder theorem for coprime polynomials. More concretely, we give a q-analogue of a nice formula due to Long and Ramakrishna [Adv. Math. 290 (2016), 773-808] and two q-supercongruences involving double series. (c) 2024 Elsevier Inc. All rights reserved.