Theorem sq0i

Description: If a number is zero, its square is zero. (Contributed by FL, 10-Dec-2006)

	Ref	Expression
Assertion	sq0i	$$⊢A=0\to A^2=0$$

Proof

Step	Hyp	Ref	Expression
1		oveq1	$$⊢A=0\to A^2=0^2$$
2		sq0	$$⊢0^2=0$$
3	1 2	eqtrdi	$$⊢A=0\to A^2=0$$