在复数域分解因式 z^n+1(a)z^n+1当n是奇数时(b)z^n-1当n是奇数时(c)z^n-1当n是偶数时

z^n+1
=∏(k=0,n-1) {z - e^[i(π/n)(2k+1)]}
z^n-1
=∏(k=0,n-1) {z - e^(i2kπ/n)}