Thực hiện phép tính: (–6x3y7 . 5x2y2 – 15x4y5) (x2 + 1).

(–6x³y⁷ . 5x²y² – 15x⁴y⁵) (x² + 1)

= (–30x⁵y⁹ – 15x⁴y⁵) (x² + 1)

= –30x⁷y⁹ – 15x⁶y⁵ – 30x⁵y⁹ – 15x⁴y⁵

= 15x⁴y⁵ (–2x³y⁴ – x – 2xy⁴ – 1).

= 15x⁴y⁵ [–2xy⁴(x² + 1) – (x + 1)]