olemus
funktsiooni f argumendi väärtus a, mille korral f(a)=0
= an input value that produces an output of 0
http://s4.thingpic.com/images/Ys/7xWpi19ZJx1LvcUFQGcs9ubS.gif
https://study.com/cimages/multimages/16/purpledots.png

ülevaateid
https://en.wikipedia.org/wiki/Zero_of_a_function
https://www.cliffsnotes.com/study-guides/algebra/algebra-ii/polynomial-functions/zeros-of-a-function
https://www.math.net/zeros-of-a-function