
theorem Th04:
  for a,b,c being Complex st a <> 0 holds (a^2 * b) * c / a^2 = b * c
  proof
    let a,b,c be Complex;
    assume
A1: a <> 0;
    (a^2 * b) * c / a^2 = b * a^2 * (c / a^2)
                       .= b * c by A1,XCMPLX_1:90;
    hence thesis;
  end;
