Simplify each expressions
(5+9z^3-3z^4)-(7z^4+4)-(6z^3+8z^2)
For the last 2 expansions there is an invisable -1 between the minus sign and the bracket.
So when you expand the bracket all the minuses become Plus and the pluses become minuses.
ex. -(x+3-y)=-1(x+3-y) = -x-3+y
(5+9z^3-3z^4)-(7z^4+4)-(6z^3+8z^2) simplify, fitst
5 + 9z^3 -3z^4 - 7z^4 - 4 -6z^3 - 8z^2 collect like terms
-3z^4 -7z^4 + 9z^3 - 6z^3 -8z^2 + 5 - 4 simplify again
-10z^4 + 3z^3 -8z^2 +1
