Theorem sq0

Description: The square of 0 is 0. (Contributed by NM, 6-Jun-2006)

	Ref	Expression
Assertion	sq0	|- ( 0 ^ 2 ) = 0

Proof

Step	Hyp	Ref	Expression
1		eqid	|- 0 = 0
2		0cn	|- 0 e. CC
3	2	sqeq0i	|- ( ( 0 ^ 2 ) = 0 <-> 0 = 0 )
4	1 3	mpbir	|- ( 0 ^ 2 ) = 0