Z Transform problem ?

[Anders]

Actually, I believe the answer is correct solving invztrans(2/(z-3),z,n) though it might seam as an odd way of expressing the answer using the Dirac (or δ) function (δ(n)=1 for n=0 else δ=0).
The resulting expression of δ may seam odd because when you try to transform the result back to the z domain, i.e. ztrans(-2*Dirac(n)+2*3^n)/3,n,z), Prime delivers the result: sum(2*3^(n-1)*z^(-n)-(2/3)*z^(-n)*Dirac(n),n,0,∞) (after some warnings), so the ztrans and the invztrans function is not handling the Dirac function smoothly in this case. (You could argue that if the invztrans function introduces δ in a result the ztrans should also handle δ smoothly and restore the result back to the original state). (I used the HP Prime virtual calculator on a PC - version: 2015 6 17 Rev. 8151).