Verified answer

I guess you mean

-3z^2 (z+2) - 4 (z^2 + 1)

...the little upward caret means the "2" is an exponent,

usually appearing in small type above the z...

The simplified form would be

-3z^3 - 6z^2 - 4z^2 - 4

= -3z^3 -10 z^2 - 4