Metamath Proof Explorer


Theorem imaeq1d

Description: Equality theorem for image. (Contributed by FL, 15-Dec-2006)

Ref Expression
Hypothesis imaeq1d.1 φ A = B
Assertion imaeq1d φ A C = B C

Proof

Step Hyp Ref Expression
1 imaeq1d.1 φ A = B
2 imaeq1 A = B A C = B C
3 1 2 syl φ A C = B C