挑战习题
1/3单选题
难度:

1.已知函数,若恒成立,则的取值范围是(    )
A [
B
C
D
提示1:
IDxpbWcgd2lkdGg9MTE5IGhlaWdodD0yMiBzcmM9Imh0dHBzOi8vcDEucWluZ2d1by5jb20vRzEvTTAwL0RFL0ZFL3JCQUNGRk5hTzlPUU44UDdBQUFEZ0xxdDdNazY4MC5wbmciPu+8jOW+l+WIsDxpbWcgd2lkdGg9MTAyIGhlaWdodD00MSBzcmM9Imh0dHBzOi8vcDIucWluZ2d1by5jb20vRzEvTTAwL0RFL0ZFL3JCQUNGRk5hTzlPeGphblFBQUFEdFdnaHBrbzIyMC5wbmciPg==
提示2:
IOaehOmAoOWHveaVsDxpbWcgd2lkdGg9MTIwIGhlaWdodD00MSBzcmM9Imh0dHBzOi8vcDIucWluZ2d1by5jb20vRzEvTTAwL0RFL0ZFL3JCQUNGRk5hTzlPeE9aUmtBQUFEOWxGVGVBWTgyNS5wbmciPg==
正确答案:QQ==
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