若 x,y,z,u屬於{1,2,3,4,5,6} 則:
(1) (x-y)(y-z)(z-u)不等於0 , 則(x,y,z,u)有__組解
(2) (x-y)(y-z)(z-u)(u-x)不等於0 , 則(x,y,z,u)有__組解
答(1)750 (2)630