単調 たんちょう減少 げんしょう数列 すうれつだったら
tanchōgenshō sū retsudattara

Noun
Da Copula

The "-tara" conditional form ("if/when…") of 単調減少数列

1. If it were a monotonically decreasing sequence.; When it is a monotonically decreasing sequence.

Tara Conditional
Mathematics