If 3x3-x = 1, then the value of 9x4 + 12x3-3x2-7x + 1999 is equal to () A. 1997B. 1999C. 2001D. 2003

If 3x3-x = 1, then the value of 9x4 + 12x3-3x2-7x + 1999 is equal to () A. 1997B. 1999C. 2001D. 2003

∵ 3x3-x = 1, ① ∵ ① × 3x: 9x4-3x2 = 3x, ② ∵ ① × 4: 12x3-4x = 4, ③ ∵ ② + ③: 9x4 + 12x3-3x2-4x = 3x + 4