Metamath Proof Explorer

Theorem neg1mulneg1e1

Description: -u 1 x. -u 1 is 1. (Contributed by David A. Wheeler, 8-Dec-2018)

Ref Expression
Assertion neg1mulneg1e1 
|- ( -u 1 x. -u 1 ) = 1

Proof

Step Hyp Ref Expression
1 ax-1cn 
 |-  1 e. CC
2 1 1 mul2negi 
 |-  ( -u 1 x. -u 1 ) = ( 1 x. 1 )
3 1t1e1 
 |-  ( 1 x. 1 ) = 1
4 2 3 eqtri 
 |-  ( -u 1 x. -u 1 ) = 1