2道数学题不太明白，请各位大侠指点. 谢谢！

bfghdggf

1. If K is positive integer, is k the square of an integer?

(1) k is divisible by 4

(2) k is divisible by exactly 4 different prime numbers

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

a. 8

b. 9

c. 18

d. 20

e. 50

himba

1、E。特殊法。令k＝20否定1），令k＝2×3×5×7否定2）。1＋2矛盾，被4整除不是质数

2、D。因为f(m)=9f(v), 所以m的十位数y 必v的y多2，所以相减可知等于20。