求解答15x+15y=xy,
问题描述:
求解答15x+15y=xy,
答
化为:xy-15x-15y+225=225
(x-15)(y-15)=225
因此x-15,y-15都是225的因数
再考虑x,y为自然数,所以有以下10组
x-15=1,3,5,9,15,25,45,75,225,-15
y-15=225,75,45,25,15,9,5,3,1,-15
得:x=16,18,20,24,30,40,60,90,240,0
y=240,90,60,40,30,24,20,18,16,0你加团队了吗?