519357823
国家队13



第二题看不清的看这一楼

自己的6做法【个人觉得这个比走向好130倍】
6

4


,6

1、Using Vieta we get that the relation equals

where . And so the maximum value is , achieved when the polynomial is ().

3、Replace the condition by . Then if , a nice solution would involve polynomials. We get that if then . Then we see . So a nice solution would involve . Then we expand and see that , works. So we're done