Answer: To find the value of 9x^-1 y^-3 for x=3 and y=1, you need to substitute 3 for x and 1 for y in the expression. Doing this gives:
9 * 3^-1 * 1^-3 = 9 * 1/3 * 1/1 = 3 * 1 = 3
So the value of 9x^-1 y^-3 for x=3 and y=1 is 3.
Note: The expression x^-1 means 1/x, so 3^-1 means 1/3. Similarly, y^-3 means 1/y^3, so 1^-3 means 1/1^3, which is equal to 1/1 or just 1.