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12024学年度第二学期期中考试数学试卷参考答案一、单选题1.B2.D3.C4.C5.B6.C7.D8.B二、选择题9.ACD10.ABD11.ABD三、填空题12.913.14.四、解答题15.(1)由,得,·································
·······································································································2分于是,整理得,解得,··
··············································································································5分所以.······························
··································································································································
······································································6分(2)原方程变形为,即,显然,·····················
···9分因此,化简整理,得,··········································································································
·································································12分而,解得,所以.···············································
···········································································································13分16.(1)二项式展开式的通项公式为(
).························2分因为第项和第项的系数比为,所以,化简得,解得,·······························································
·················································································4分所以().令,得,·········
····················································································································································
················6分{#{QQABBQQAgggoQIJAABhCUQHwCAGQkBACCKoGxBAEIAIBiANABAA=}#}2所以常数项为第项.···································
·················································································································································
··········7分(2)设展开式中系数最大的项是第项,则,·····························································11分解得.···············································
·················································································································································
·······················13分因为,所以或,所以展开式中系数最大的项是第项和第项.·············15分17.(1)由,得,令,则,解得;················································
············································································································
···········1分当时,,所以,所以,··········3分所以当时,,有,········································6分又满足上式,所以,得,所以数列是
首项为0,公差为1的等差数列.···························································································
····························8分(2)由(1)知,所以,················································································
····················9分所以,故,两式相减,得{#{QQABBQQAgggoQIJAABhCUQHwCAGQkBACCKoGxBAEIAIBiANABAA=}#}3,所以.······························
····································································································································
······················································15分18.(1)由函数,可得,····································
····················································································2分令,即,解得;令,即,解得,所以函数在区间单调递减,单调递增,························
······················································4分当时,取得极小值,极小值为,无极大值.·····························································
············6分(2)由不等式恒成立,即恒成立,即对于任意,不等式恒成立,································································
····················································8分设,可得,令,即,解得;令,即,解得,所以在上单调递减;在单调递增,························································
·······················12分所以,当时,函数取得极小值,同时也时最小值,,·············································14分所以,即,所以实数的取值范围为.·······························
··························17分19.(1)函数的定义域为,,当时,,所以在上单调递增;当时,由得,所以在上单调递增;由得,所以在上单调递减;故时,所以在上单调递增;············
············································································································2分当时,在上单调递增,
在上单调递减;·············································4分(2)由f(x)的图象恒在x轴上方,可得f(x)=x−mlnx>0{#{QQABBQQAggg
oQIJAABhCUQHwCAGQkBACCKoGxBAEIAIBiANABAA=}#}4因为x>0且m>0,不等式两边同时除以mx,可得1���>������������···········6分设h(x)=������������可得h’(x)=1−�����������
�2令h’(x)>0,解得0<x<e令h’(x)<0,解得x>e所以h(x)在(0,e)上单调递增,在(e,+∞)上单调递减所以当x=e时h(x)取得最大值,h(e)=1���···················
···························································································8分所以1���>
h(x)max即1���>1���所以m的范围是(0,e)······························································9分(3)证明:,,由(1)可知,当时,在上是增函
数,故不存在不相等的实数,使得,所以.由得,即,···············11分不妨设,则,则,要证,只需证,即证,只需证,·······························································
·····························································14分令,则只需证,即证,令,则,所以在上是增函数,所以,从而,故.·············································
·····························································································································
···········17分{#{QQABBQQAgggoQIJAABhCUQHwCAGQkBACCKoGxBAEIAIBiANABAA=}#}