若|x-4y|+ (y-2)^2=0,则:
|x-4y|=0且y-2=0
解得：y=2,x=8
3x+4y=32
当a-b/a+b=2,
(a-b/a+b)^2-3*(a-b/a+b）=2^2-3*2=-2