To solve the expression 9/2n-6 - n^2/2n-6, we first need to find a common denominator. The common denominator for both fractions is (2n-6).

So, the expression becomes:

9/(2n-6) - n^2/(2n-6)

Now, we can combine the fractions:

(9 - n^2)/(2n-6)

We can simplify the numerator by factoring out a negative sign:

-(n^2 - 9)/(2n-6)

Now, we can factor the numerator using the difference of squares formula:

-(n+3)(n-3)/(2n-6)

Now, we can simplify further by factoring out a common factor of 3 in the numerator:

-3(n+3)(n-3)/(2n-6)

Finally, we can simplify the expression by canceling out the common factor of 3 in the numerator and denominator:

-3(n+3)/(2n-6)

Therefore, the solution to the expression 9/2n-6 - n^2/2n-6 is -3(n+3)/(2n-6).