If z0 is a zero of a (real-valued) linear - phase FIR filter then following is/are also zero/zeros of a (real-valued) linear - phases FIR filter,
1
\(z_0^*\)
2
\(\frac{1}{{{z_0}}}\)
3
\(\frac{1}{{{z_0}}}\), \(z_0^*\) and \(\frac{1}{{z_0^*}}\)
4
\(\frac{1}{{{z_0}}}\) and \(\frac{1}{{z_0^*}}\)