<prompt> Tathmini sqrt5 sqrt21 sqrt5 - sqrt21.  <response>: Kuweka sawa usemi uliotolewa, tuna anzaaligned leftsqrt5sqrt21sqrt5-sqrt21kulia2 5 sqrt21 5-sqrt21 2sqrt5sqrt215-sqrt21 10 2sqrt 4 14. endalignedKwa sababu usemi uliotolewa ni chanya waziwazi, thamani yake lazima iwe sqrt14. 