15.若方程x2+3x+1=0的两个根分别是x1,x2,则x12x2+x1x22为( )
0 308605 308613 308619 308623 308629 308631 308635 308641 308643 308649 308655 308659 308661 308665 308671 308673 308679 308683 308685 308689 308691 308695 308697 308699 308700 308701 308703 308704 308705 308707 308709 308713 308715 308719 308721 308725 308731 308733 308739 308743 308745 308749 308755 308761 308763 308769 308773 308775 308781 308785 308791 308799 366461
| A. | 3 | B. | -3 | C. | $\frac{1}{3}$ | D. | -$\frac{1}{3}$ |