Rút gọn biểu thức: 2x(x – 4)² – (x + 5)(x – 2)(x + 2) + 2(x + 5)² – (x – 1)².

Ta có 2x(x – 4)² – (x + 5)(x – 2)(x + 2) + 2(x + 5)² – (x – 1)²

= 2x(x² – 8x + 16) – (x + 5)(x² – 4) + 2(x² + 10x + 25) – (x² – 2x + 1)

= 2x³ – 16x² + 32x – (x³ – 4x + 5x² – 20) + 2x² + 20x + 50 – x² + 2x – 1

= (2x³ – x³) + (–16x² – 5x² + 2x² – x²) + (32x + 4x + 20x + 2x) + (20 + 50 – 1)

= x³ – 20x² + 58x + 69.