1 1 -1 1 -2 1 1 -3 3 -1 1 -4 6 -4 1 1 -5 10 x 5 -1 1 -6 15 -20 15 -6 1 x是?

问题描述:

1 1 -1 1 -2 1 1 -3 3 -1 1 -4 6 -4 1 1 -5 10 x 5 -1 1 -6 15 -20 15 -6 1 x是?