Theorem 0xr

Description: Zero is an extended real. (Contributed by Mario Carneiro, 15-Jun-2014)

	Ref	Expression
Assertion	0xr	|- 0 e. RR*

Proof

Step	Hyp	Ref	Expression
1		ressxr	|- RR C_ RR*
2		0re	|- 0 e. RR
3	1 2	sselii	|- 0 e. RR*