y=(1-x)/(2x+3)
y(2x+3)=1-x
(2y+1)x=1-3y
所以x=(1-3y)/(2y+1),当2y+1不=0时成立.即Y不=-1/2.
所以,值域是(-无穷,-1/2)U(-1/2,+无穷)