“…He determined that only seven such triples exist, namely (1, 1, 1), (1,1,2), (1,1,4), (1,1,5), (1,2,2), (1,2,3) and (1,2,4). Recently, in [8], [16], and [18], Z.-W. Sun et al effectively determine all αx 2 + βT y + γT z and αx 2 + βy 2 + γT z that are universal.…”