GWD30-Q2:

nomadwander

GWD30-Q2:

d

实在不知道题目如何对应，找不到讨论贴。

麻烦大家!

Q2:

The function f is defined for each positive three-digit integer n by f(n) = 2^x3^y5^z, where x, y and z are the hundreds, tens, and units digits of n, respectively.  If m and v are three-digit positive integers such that f(m) = 9f(v), then m-v = ?

 

 

A.    8

B.    9

C.    18

D.    20

bluespecter1

f(m) = 9f(v)也就是f(m)=2^x3^y5^z，m=xyz 如：m=139
9f(v)=3^2*2^x3^y5^z=2^x3^(y+2)5^z，v=x(y+2)z 又 x(y+2)z=139，
即y+2=3（指十位）--> v=119
m-v=20