(x-1)/(x^2-5x+6)+(x-2)/(x^2-4x+3)+(x-3)/(x^2-3x+2) = (x-1)/{(x-2)(x-3)} + (x-2)/{x-1)(x-3)} + (x-3)/{(x-1)(x-2)}= { (x-1)^2 + (x-2)^2 + (x-3)^2 } / { (x-1)(x-2)(x-3) }= (x^2-2x+1+x^2-4x+4+x^2-6x+9) / ...