Prerequisites - P.2 - Exponents and Radicals - Exercises - Page 24: 14

a) $\frac{7}{12}$ b)$\frac{1}{81}$

a) $3^{-1}+2^{-2}=\frac{1}{3^1}+\frac{1}{2^2}=\frac{1}{3}+\frac{1}{4}=\frac{4}{12}+\frac{3}{12}=\frac{7}{12}$ b)$(3^{-2})^2=3^{-2\cdot2}=3^{-4}=\frac{1}{3^4}=\frac{1}{3\cdot3\cdot3\cdot3}=\frac{1}{81}$