If x/x=1, then 0/0=? Is it =1 or =0 or =infinity ?

這是未有定義的，因為在定義除法(division)時，已經將分母為0的情況剔除了，所以 x/0是未有定義的，即是不合除法的法則。

/ : Rx(R\{0}) ---> R ( / 為除法的代表附號)

infinity其實也不是實際的一個數字，只是用來代表一個概念。

0/0 = undefined~
it's becoz everything devided by 0 is useless.
so when you press 0/0 on your caltor...
maths error will shown.

It absolutely won't be 0 or 1.
All the equations if the denominator(分母) equals to 0, then basically it equals to infinity.

Of course, 0/0 = 0

for any x/0 = infinity!!!