treat [,] as 聯集(U)
treat (,) as 交集
then you can prove:
對於自然數k,m,n,不等式[k,m]x[m,n]x[n,k]>=[k,m,n]2
其中[a,b]為a,b的最小公倍數
by
N(AUB)+N(BUC)+N(CUA) >=2*N(AUBUC)
--------------------
scsnake 寫到:怪解法∼∼
如圖,原式即為2(a+b+c)+3(d+e+f+g)≧2(a+b+c+d+e+f+g)
→d+e+f+g≧0→等號成立於A,B,C兩兩獨立時