kx-12=3x+3k,x为整数,求k.
问题描述：
kx-12=3x+3k,x为整数,求k.
答
由kx-12=3x+3k
（k-3)x=3k+12
x=(3k+12)/(k-3)
=3(k+4)/(k-3)
=[3(k-3)+21]/(k-3)
x为整数，只需满足21/(k-3)为整数即可
所以 k=10 或 k=6
答
(k-3)x=3k+12
x=(3k+12)/(k-3)
=3+21/(k-3)
即21能被(k-3)整除,k-3=1或3或7或21
k=4或6或10或24