GWD30-02

[navywhite0425]

Q2:
The function f is defined for each positive three-digit integer n by f(n) = 2x3y5z, 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
E. 80

附帶一提
x,y,z分別是2.3.5三個數字的次方

第一次po版
抱歉= =

奇怪
為啥我總覺得他少給我一些東西
向各位高手求救!!

[StanleyHuang]

答案應該是 (D)20 吧？
f(m)=9f(v)=3[sup]2[/sup]*f(v)
由 3[sup]2[/sup]可知，m的十位數比v多2
所以 m-v = 20