设a 1 、b 1 、c 1 、a 2 、b 2 、c 2 均为非零实数,不等式a 1 x 2 +b 1 x+c 1 >0和a 2 x 2 +b 2 x+c 2 >0的分别为集合M和N,那么“ a 1 a 2 = b 1 b 2 = c 1 c 2 ”是“M=N”的______条件.
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