作者yuchiao0921 (挑战在我就在)
看板Math
标题[中学] 重复组合
时间Sat Jun 18 00:17:18 2011
X1+X2+X3+X4+X5=21
X1~X5都是非负整数解
请问满足下列条件有几组解
0<=X1<=3,1<=X2<4,X3>=15
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1F：推 KitWoolsey :把X2跟X3的1跟15先扣掉 变成总合=5 06/18 00:19
2F：→ KitWoolsey :0<=X1<=3,0<=X2<=2 救好解了吧 06/18 00:20
3F：→ yuchiao0921 :谢谢 06/18 00:57