计算,12/(m²-9)-2/(m-3)((x²-4)/(x²-4x+4)-(x-2)/(
2个回答

12/(m²-9)-2/(m-3)

=12/(m+3)(m-3)-2(m+3)/(m+3)(m-3)

=(12-2m-6)/(m+3)(m-3)

=-2(m+3)/(m+3)(m-3)

=-2/(m-3)

((x²-4)/(x²-4x+4)-(x-2)/(x+2))÷x/(x-2)

=[(x+2)(x-2)/(x-2)²-(x-2)/(x+2)]×(x-2)/x

=[(x+2)(x-2)/(x-2)²-(x-2)/(x+2)]×(x-2)/x

=[(x+2)/(x-2)-(x-2)/(x+2)]×(x-2)/x

=[(x+2)²-(x-2)²]/(x+2)(x-2)×(x-2)/x

=4x/(x+2)(x-2)×(x-2)/x

=4/(x+2)