We assume you mean
.. f(x) = -3*x^3 -2
.. g(x) = -3*x^-3
Then
.. f(-3) = -3*(-3)^3 -2 = -3*(-27) -2 = 81 -2 = 79
.. g(4) = -3*4^-3 = -3/64
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It is helpful if you use ordinary lower-case letters for variables (except in some formulas where upper-case letters are used). The symbol "×" is used to signify multiplication, so leads to confusion when you try to use it for a variable. In plain text, the exponentiation operator is a caret (^), so x^2 means "x squared", for example. If the exponent is supposed to include an arithmetic operation, then it needs to be enclosed in parentheses, x^(3y-4), for example.