4. Упростите: a) $$a^2 \cdot a^4 : a^3$$; б) $$\frac{x^{\frac{1}{4}} \cdot x^2}{x^4}$$; в) $$(c^{\frac{1}{3}})^2 \cdot c^{-\frac{3}{2}}$$

a) $$a^2 \cdot a^4 : a^3 = a^{2+4-3} = a^3$$ б) $$\frac{x^{\frac{1}{4}} \cdot x^2}{x^4} = \frac{x^{\frac{1}{4} + 2}}{x^4} = \frac{x^{\frac{9}{4}}}{x^4} = x^{\frac{9}{4} - 4} = x^{\frac{9-16}{4}} = x^{-\frac{7}{4}}$$ в) $$(c^{\frac{1}{3}})^2 \cdot c^{-\frac{3}{2}} = c^{\frac{2}{3}} \cdot c^{-\frac{3}{2}} = c^{\frac{2}{3} - \frac{3}{2}} = c^{\frac{4-9}{6}} = c^{-\frac{5}{6}}$$