C) \( x^4 - 2x^3 + 5x^2 - 2x + 1 = 0 \) d) \( (x + 2)(x + 3)(x + 4)(x + 6) = 30x^2 \) e) \( (12x + 7)^2(3x + 2)(2x + 1) = 3 \)

c) \( x^4 - 2x^3 + 5x^2 - 2x + 1 = 0 \)
d) \( (x + 2)(x + 3)(x + 4)(x + 6) = 30x^2 \)
e) \( (12x + 7)^2(3x + 2)(2x + 1) = 3 \)