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 ) ) ) |