方程有实数根所以判别式≥04(a+1)²-4(3a²+4ab+4b²+2)≥0a²+2a+1-(3a²+4ab+4b²+2)≥0-2a²+2a-4ab-4b²-1≥0(-a²+2a-1)-(a²+4ab+4b²)≥0-(a-1)²-(a+2b)&#...