9,化简,
原式
=(2m²-4m-m²-2m)/(m²-4) * (m²-4)/m
=(m²-6m)/(m²-4)* (m²-4)/m
=m-6
10,化简,
(1)原式
=(x-1-x-1)/(x²-1)* (x²-1)/2
=-2/(x²-1)*(x²-1)/2
=-1
(2)原式
=(a²-4+4)/(a²-4)*(a-2)/a
=a²/(a+2)(a-2)*(a-2)/a
=a/(a+2)
(3)原式
=(m+1)/m * (m-1)²/(m+1)(m-1)
=(m-1)/m
11,原式
=(x²-2x+1+2x)/(x²-1) * (x²-1)
=x²+1
无论x=-2还是x=2 ,x²+1都等于5