Theorem iuneq1i

Description: Equality theorem for indexed union. (Contributed by Glauco Siliprandi, 3-Mar-2021)

	Ref	Expression
Hypothesis	iuneq1i.1	|- A = B
Assertion	iuneq1i	|- U_ x e. A C = U_ x e. B C

Proof

Step	Hyp	Ref	Expression
1		iuneq1i.1	|- A = B
2		iuneq1	|- ( A = B -> U_ x e. A C = U_ x e. B C )
3	1 2	ax-mp	|- U_ x e. A C = U_ x e. B C