Phân tích nhân tử \( 3 \cdot (x - 1) \cdot (x - 2) - x \cdot (3x + 1) \cdot (1 - x) \)

----- Nội dung ảnh -----
13) \( 3 \cdot (x - 1) \cdot (x - 2) - x \cdot (3x + 1) \cdot (1 - x) \)

14) \( -4x \cdot (x + 3) \cdot (x - 4) - 3x \cdot (x^2 - x + 1) \)

15) \( -3 \cdot (x + 4) \cdot (x - 7) + 7 \cdot (x - 5) \cdot (x - 1) \)

16) \( -2 \cdot (x - 3) \cdot (2x^2 + 1) + x \cdot (4x + 1) \cdot (x + 2) \)