metamath/valid/algebra-manipexpr-apbeq2cceqiacpbceqm2.mm (16 lines of code) (raw):
${
algebra-manipexpr-apbeq2cceqiacpbceqm2.0 $e |- ( ph -> A e. CC ) $.
algebra-manipexpr-apbeq2cceqiacpbceqm2.1 $e |- ( ph -> B e. CC ) $.
algebra-manipexpr-apbeq2cceqiacpbceqm2.2 $e |- ( ph -> ( A + B ) = ( 2 x. C )
) $.
algebra-manipexpr-apbeq2cceqiacpbceqm2.3 $e |- ( ph -> C e. CC ) $.
algebra-manipexpr-apbeq2cceqiacpbceqm2.4 $e |- ( ph -> C = _i ) $.
$( (Contributed by Stanislas Polu, 14-Sep-2020.) $)
algebra-manipexpr-apbeq2cceqiacpbceqm2 $p |- ( ph -> ( ( A x. C ) + ( B x. C
) ) = -u 2 ) $=
( caddc co cmul c2 cneg adddird ci oveq12d 2cnd a1i 2cn wcel ax-icn mulassd cc
oveq1d oveq2d ixi oveq2i wceq neg1cn mulm1i mulcomli syl5eq eqtrd 3eqtrd c1
eqtr3d ) ABCJKZDLKZBDLKCDLKJKMNZABCDEFHOAUSMDLKZPLKMDPLKZLKZUTAURVADPLGI
QAMDPARHPUDUAAUBSUCAVCMPPLKZLKZUTAVBVDMLADPPLIUEUFAVEMUPNZLKZUTVDVFMLUGUHVG
UTUIAVFMUTUJTMTUKULSUMUNUOUQ $.
$}