\[ 4x^4 \cdot (-2x^3)^2 = 4x^4 \cdot (4x^6) = 16x^{10} \]
\[ (3x - 1)(3x + 1) + (3x + 1)^2 = (9x^2 - 1) + (9x^2 + 6x + 1) = 9x^2 - 1 + 9x^2 + 6x + 1 = 18x^2 + 6x \]
Ответ: а) 16x^{10}; б) 18x^2 + 6x