F8:  -(a+b) = (-a)+(-b)

"-(a+b) = (-a)+(-b)  for all  a,b  [in]  R.  For both are solutions of the equation  x+(a+b)=0."  (see ita-2-1-15-pg18)

ita


Converted [ in part ] by Mathematica      December 4, 2007