问题
填空题
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答案
和2 9-3a
的分母分别是9-3a=-3(a-3)、a2-9=(a+3)(a-3),故最简公分母是3(a+3)(a-3);a-1 a2-9
通分后为
=-2 9-3a
,2(a+3) 3(a+3)(a-3)
=a-1 a2-9
.3(a-1) 3(a+3)(a-3)
故答案为3(a+3)(a-3);-
,2(a+3) 3(a+3)(a-3)
.3(a-1) 3(a+3)(a-3)