由|a+b-6|+|3a+3b-6|=0知|a+b-6|=0;|3a+3b-6|=0;
|a+b-6|=0知a+b=6
|3a+3b-6|=|a+2(a+b)-6|=|a+12-6|=|a+6|=0,所以a=-6.b=12
(a-b)^2=18^2=324
由|a+b-6|+|3a+3b-6|=0知|a+b-6|=0;|3a+3b-6|=0;
|a+b-6|=0知a+b=6
|3a+3b-6|=|a+2(a+b)-6|=|a+12-6|=|a+6|=0,所以a=-6.b=12
(a-b)^2=18^2=324