(9x^4-7x^2+6x-2): (3x^2-2x+1) (15x^5+6x^4-20x^2-8x): (3x^3-4) (12x^5-9x^4+8x^2-6x): (4x^2-3x)

(9x^4-7x^2+6x-2):(3x^2-2x+1)=(3x^2-2x+1)(3x^2+2x-2)/(3x^2-2x+1)=3x^2+2x-2=3(x-(√7-1)/3)(x+(√7+1)/3))=1/3(3x-√7+1)(3x+1+√7);
(15x^5+6x^4-20x^2-8x):(3x^3-4)=(3x^3-4)(5x^2+2x)/(3x^3-4)=5x^2+2x=x(5x+2)
(12x^5-9x^4+8x^2-6x):(4x^2-3x)=(12x^4-9x^3+8x-6)*/(4x-3)=(3x^3+2)(4x-3)/(4x-3)=3x^2+2