2004/3+2003/3
=2004/3+2004/3-1/3
=4008/3-1/3
=1336-1/3=1335又(2/3)
101/(-2)+100/(-2)
=100/(-2)+100/(-2)-1/2
=-100又(1/2)
(x+1)(x+2)+1/4
=x^2+3x+9/4
=(x+3/2)^2