[求助]OG11数学4.5

游魂

54.

A B C D E F

City A
City B City C City D City E City F

In the table above, what’s the least number of table entries that are needed to show the mileage between each city and each of the other five cities?

A) 15

B) 1

C) 5

D) 0

E) 6

169.If n is a positive integer and n² is divisible by 72, then the largest positive integer that must divide n is

A) 6

B) 12

C) 24

D) 36

E) 48

linlin2008

169. 72=2*2*3*3*2 so least n^2=2*2*3*3*2*2=144 n=12, then the largest positive integer that must divide n is 12. answer: B am i right?

54, 不好意思刚才没看清楚题目，答案应当是（6*6-6）/2=15，看过地图没有，地图上经常会有主要城市间的距离表，是一样的东西。或者用排列组合作 （6个里任选两个）6*5/2=15

游魂

many thanks !!!