# What is x/y/0 ?

##### 1 Answer

#### Explanation:

**When dealing with arithmetic of ordinary numbers, division by #0# is always undefined, so any resulting expression is undefined.**

So both

There are at least two non-ordinary contexts in which it may be defined.

They are called the "real projective line"

Both of these extensions of ordinary numbers add a single point "at infinity"

For example:

For any

#x+oo = oo+x = oo#

For any non-zero

#x/oo = 0#

#x/0 = oo#

The following expressions are all indeterminate:

#0/0#

#oo/oo#

#oo-oo#

#0*oo#

However, we do find that if

#x/(y/0) = x/oo = 0#