Computing inverse Z-transform

Hi,

I need to compute the inverse Z-transform of following equation:

and here is my code:

syms z k kp
F = (z^2-0.286*z)/(.713*kp*z^5-.713*kp*z^4+z^2-1.286*z+.286);
iztrans(F, z, k)

Response:

ans =

- (714*(kroneckerDelta(k, 0) - 1))/(713*kp + 714) - (symsum(-(204204*r5^k - r5*r5^k*(203918*kp + 714000) + 509082*kp*r5^k*r5^2 + 509082*kp*r5^k*r5^3)/(3000*r5 - 1144), r5 in RootOf(713*kp*z4^4 + 1000*z4 - 286, z4)) - 714*kroneckerDelta(k, 0))/(713*kp + 714)

Excuse my limited knowledge on the matter. But what are r5 and symsum and kroneckerDelta. Can someone decipher the answer for me please?