Why can't telemachus string the bow on his fourth try? odysseus waves him off. his strength fails him. he wants to give the suitors a false sense of confidence. he wants to demonstrate to the suitors that the task is impossible.

I believe that the best answer for this question is "Odysseus waves him off." After he tries four times, it appears as though Telemachus might actually succeed in stringing the bow, but the beggar (who is Odysseus in disguise) waves him off and attempts to do it instead. Telemachus obliges to the beggar and gives the bow to the next individual in line. Hope this helps.