|a+2b+3|+（3a-b）²-10（3a-b）+25=0|a+2b+3|+（3a-b）²－2×5×（3a-b）+5²=0|a+2b+3|+(3a－b－5)²=0因为|a+2b+3|与(3a－b－5)²分别≥0,所以要想|a+2b+3|+(3a－b－5)²=0,必须是a+2b+...