Final answer:
The expression involves exponentiation with an unknown variable, making it impossible to simplify without the specific value of z.
Step-by-step explanation:
The expression -9x(-3)^z+2x cannot be simplified without knowledge of the value of variable z. This is because (-3)^z represents exponentiation, which is a non-linear operation, and its result can vary dramatically depending on the value of z. As such, without a specific value, you cannot simplify the term involving z with the other terms. In mathematics, to simplify an expression, like terms must be combined, which is not possible here since x and (-3)^z are not like terms. Moreover, negative exponents flip the construction to the denominator according to mathematical rules, but since z is not given a constant value, we cannot definitively apply this operation either.