The expression in fraction form will be:

The denominator can be multiplied to the numerator by taking its reciprocal as shown below:

There are no common factors, so the expression can not be simplified any further.
^ means to the power of with nothing after it, it's miss-used. Solving without the ^ symbol it is -2xy with the ^ symbol it's irrational and cannot be solved.
The value of the expression (2)^6 is 64.
Write it in descending order of degree
that is
-g^3 + 6g^2 + 4g - 9