(2x-y-5)²+3x+4y-2的绝对值=02x-y-5=03x+4y-2=0x=2y=-1
(2x-y-5)²≥0,|3x-4y-2|≥0 且：(2x-y-5)²+|3x+4y-2|=0所以有：2x-y-5=03x+4y-2=0解得：x=2 ,y=-1
