单选题若关于x的方程x2＋2x＋a＝0不存在实数根，则a的取值范围是（ ）．Aa＜1Ba＞1Ca≤1Da≥1
单选题
若关于x的方程x2＋2x＋a＝0不存在实数根，则a的取值范围是（ ）．
A
a＜1
B
a＞1
C
a≤1
D
a≥1
参考解析
解析：
由4－4a＜0，故a＞1．
由4－4a＜0，故a＞1．
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