In 2-3 sentences describe why the only way an infinite geometric series has a sum is if r<1

Okay so i didn't get this problem petro bought 8 tickets to a basketball game he paid a total of $200 write an equation to determine whether each ticket cost $26 or $28 so i didn't get this question so yeahyou have a good day.

Circle d circumscribes abc and abe. which statements about the triangles are true? statement i: the perpendicular bisectors of abc intersect at the same point as those of abe. statement ii: the distance from c to d is the same as the distance from d to e. statement iii: bisects cde. statement iv: the angle bisectors of abc intersect at the same point as those of abe. a. i only b. i and ii c. ii and iv d. i and iii e. iii and iv

Acertain volume of water contains 100000 hydrogen atoms and 50,000 oxygen atoms how many hydrogen atoms are in a volume of water containing 4 million oxygen atoms