证明行列式等于a0x^(n-1)+a1x(n-2)+...+a[n-1]
行列式a0-10...00
a1x-1...00
..................
a[n-2]00...x-1
a[n-1]00...0x
[]为下标
证明该行列式等于a0x^(n-1)+a1x(n-2)+...+a[n-1]