Theorem sq0id

Description: If a number is zero, its square is zero. Deduction form of sq0i . Converse of sqeq0d . (Contributed by David Moews, 28-Feb-2017)

	Ref	Expression
Hypothesis	sq0id.1	$$⊢\phi \to A=0$$
Assertion	sq0id	$$⊢\phi \to A^2=0$$

Proof

Step	Hyp	Ref	Expression
1		sq0id.1	$$⊢\phi \to A=0$$
2		sq0i	$$⊢A=0\to A^2=0$$
3	1 2	syl	$$⊢\phi \to A^2=0$$