An exponent signifies repeated multiplication.
[tex]x\cdot x\cdot x=x^{3}[/tex] the factor x is repeated 3 times
Exponents can be added and subtracted to express the effects of multiplication and division.
[tex]\dfrac{x\cdot x\cdot x\cdot x\cdot x}{x\cdot x\cdot x}=\dfrac{x^{5}}{x^{3}}\\\\=\dfrac{x\cdot x\cdot x}{x\cdot x\cdot x}\cdot x\cdot x=x\cdot x\\\\=x^{(5-3)}=x^{2}[/tex]
The addition and subtraction of exponents works the same even when there are more denominator factors than numerator factors.
[tex]\dfrac{x\cdot x\cdot x}{x\cdot x\cdot x\cdot x\cdot x}=\dfrac{x^{3}}{x^{5}}=\dfrac{1}{x^{2}}\\\\=x^{(3-5)}=x^{-2}[/tex]
That is, a negative numerator exponent is the same as a positive denominator exponent and vice versa. You can move a factor with an exponent from denominator to numerator and change the sign of the exponent, and vice versa.
Your expression has 3 in the denominator with a negative exponent. It can be moved to the numerator and the exponent changed to positive:
[tex]\dfrac{1}{3^{-2}}=3^{2}\\\\=3\cdot 3=\bf{9}[/tex]
