split this into partial fraction
z/(z^2-1)(z^2+4)

Do you mean this:


\frac z {(z^2-1)(z^2+4)}
?


Note that z^2-1 factors to (z+1)(z-1), so you need to find values of constants A, B, C, and D that sastify this:


\frac z {(z^2-1)(z^2+4)} = \frac A {z+1} + \frac B {z-1} + \frac {Cz + D} {{z^2 + 4}



Can you take it from here?