Упростите выражение: \((\frac{a^2}{3}-\frac{x}{2})(\frac{a^4}{9}+\frac{a^2x}{6}+\frac{x^2}{4}).\)

• \(\frac{a^6}{27}+\frac{x^3}{8}\)
• \(\frac{a^5}{27}-\frac{x^3}{8}\)
• \(\frac{a^6}{27}-\frac{x^3}{8}\)