Вычислите: a) 3⁻³; 2⁻⁴; 11⁻²; б) (-9)⁻²; (-5)⁻³; (-2)⁻⁶; в) 1⁻²⁵; (-1)⁻¹⁷; (-1)⁻²⁰; г) 15⁰; (-12)⁰; (-1)⁰.

a) $$3^{-3} = \frac{1}{3^3} = \frac{1}{27}$$ $$2^{-4} = \frac{1}{2^4} = \frac{1}{16}$$ $$11^{-2} = \frac{1}{11^2} = \frac{1}{121}$$ б) $$(-9)^{-2} = \frac{1}{(-9)^2} = \frac{1}{81}$$ $$(-5)^{-3} = \frac{1}{(-5)^3} = \frac{1}{-125} = -\frac{1}{125}$$ $$(-2)^{-6} = \frac{1}{(-2)^6} = \frac{1}{64}$$ в) $$1^{-25} = \frac{1}{1^{25}} = \frac{1}{1} = 1$$ $$(-1)^{-17} = \frac{1}{(-1)^{17}} = \frac{1}{-1} = -1$$ $$(-1)^{-20} = \frac{1}{(-1)^{20}} = \frac{1}{1} = 1$$ г) $$15^0 = 1$$ $$(-12)^0 = 1$$ $$(-1)^0 = 1$$