Description: Specialization of absmuld with absidd . (Contributed by Stanislas Polu, 9-Mar-2020)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | absmulrposd.1 | |- ( ph -> 0 <_ A ) | |
| absmulrposd.2 | |- ( ph -> A e. RR ) | ||
| absmulrposd.3 | |- ( ph -> B e. RR ) | ||
| Assertion | absmulrposd | |- ( ph -> ( abs ` ( A x. B ) ) = ( A x. ( abs ` B ) ) ) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | absmulrposd.1 | |- ( ph -> 0 <_ A ) | |
| 2 | absmulrposd.2 | |- ( ph -> A e. RR ) | |
| 3 | absmulrposd.3 | |- ( ph -> B e. RR ) | |
| 4 | 2 | recnd | |- ( ph -> A e. CC ) | 
| 5 | 3 | recnd | |- ( ph -> B e. CC ) | 
| 6 | 4 5 | absmuld | |- ( ph -> ( abs ` ( A x. B ) ) = ( ( abs ` A ) x. ( abs ` B ) ) ) | 
| 7 | 2 1 | absidd | |- ( ph -> ( abs ` A ) = A ) | 
| 8 | 7 | oveq1d | |- ( ph -> ( ( abs ` A ) x. ( abs ` B ) ) = ( A x. ( abs ` B ) ) ) | 
| 9 | 6 8 | eqtrd | |- ( ph -> ( abs ` ( A x. B ) ) = ( A x. ( abs ` B ) ) ) |