а) \(3\pi^2 y^4\cdot y\cdot x^3y^2 = 3\pi^2x^3y^{4+1+2}=3\pi^2x^3y^7\).
б) \(0.5a^4\cdot(3b^2c)^2 = 0.5a^4\cdot9b^4c^2 = 4.5a^4b^4c^2\).
Ответ: а) \(3\pi^2x^3y^7\); б) \(4.5a^4b^4c^2\).