axbycz = (b+c)(a+c)(a+b) >= 8abc
所以xyz >= 8
設(shè)x>=y>=z
若x>=2 ,y>=2 ,z>=2
那么
2(a+b+c) = ax+by+cz >= 2(a+b+c)
所以此時給出x = y = z = 2
若z = 1
那么
c = a+b
ax = b+c = a+2b =>x = 1 + 2b/a
by = a+c = 2a+b =>y = 1 + 2a/b
x和y都是整數(shù)
所以a=b
此時給出x = y = 3
綜合得x y z可取值為(2,2,2)和(3,3,1)
乘積可能為8或9