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“-2≤a≤2”是“实系数一元二次方程x2+ax+1=0有虚根”的. A.必要不...
“-2≤a≤2”是“实系数一元二次方程x2+ax+1=0有虚根”的.
A.必要不充分条件
B.充分不必要条件
C.充要条件
D.既不充分也不必要条件
考点分析:
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