"This table is low."
I wish Duolingo introduced the Kanji before giving us the reading so that I wouldn't have to look them all up myself -_-
I accidentally clicked on next before adding です at the end and it was right??
Yes, that's still a grammatically correct answer. Since ひくい is an い adjective, the です is only needed in formal speech. In informal speech, sentences ending in an い adjective omit the です, whereas if it was a な adjective (like きれい for example), the です would be replaced with だ.
Yes, that would be incorrect. As @KagayakuSeiza's comment points out above, when the sentence ends in an い-adjective (e.g. ひくい、あつい), the informal form simply loses the です. With a な-adjective (e.g. きれい、しずか), the informal form changes です to だ.