用简便方法计算1/(x^2-5x+6)+1/(x^2-3x+2)
1/(x^2-5x+6)+1/(x^2-3x+2)
=1/(x-2)(x-3)+1/(x-1)(x-2)
=1/(x-3)-1/(x-2)+1/(x-2)-1/(x-1)
=1/(x-3)-1/(x-1)
=2/(x^2-4x+3)
1/(x^2-5x+6)+1/(x^2-3x+2)
=1/(x-2)(x-3)+1/(x-1)(x-2)
=1/(x-3)-1/(x-2)+1/(x-2)-1/(x-1)
=1/(x-3)-1/(x-1)
=2/(x^2-4x+3)