2022年专项练习题集-不等式恒成立问题 .pdf
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1、20XX 年专项练习题集-不等式恒成立问题三级知识点:不等式恒成立问题介绍:不等式恒成立问题以含参不等式“恒成立”为载体,镶嵌函数、方程、不等式等内容,综合性强,能力要求高,为历年高考试题的热点。选择题1不等式2230mxmx对一切 xR 恒成立,则实数m的取值范围是()A30mB30mC30mD30m【分值】5【答案】D【易错点】容易忽略0m的情形。【考查方向】本题主要考查了含参数的二次不等式的恒成立问题。【解题思路】对m的分类讨论,(1)0m,(2)当0m时,结合二次函数图象,二次函数应该开口向下,判别式小于等于零,列出满足的条件求解【解析】当0m时不等式化为30恒成立;当0m时需满足00
2、m,所以30m,综上可知实数a的取值范围是30m.2已知2()3f xaxbx,不等式0)(xf的解集是(1,3),若对于任意 1,2x,不等式()10f xm恒成立,m的取值范围是()A 14,10B(,10C(,14D 14,14【分值】5【答案】C【易错点】不会求出a,b 的值,不会转化恒成立问题。【考查方向】本题主要考查了函数的解析式,考查恒成立问题,解题的关键是利用好不等式的解集与方程解之间的关系,将恒成立问题转化为函数的最值加以解决【解题思路】(1)根据不等式的解集与方程解之间的关系可知230axbx的两根为1,3,从而可求,a b 的值,进而可求fx的解析式;(2)要使对于任意
3、1,2x,不等式()10f xm恒成立,只需min()10f xm即可,从而可求m的范围【解析】不等式()0f x的解集是(1,3),所以1和3是方程230axbx的两个根,由韦 达 定 理 得1,2ab 所 以2()23f xxx,所 以()10fxm恒 成 立 等 价于2213xxm恒成立,由22213(1)1414xxx,所以14m选 C3对任意的实数x,不等式30 xxa恒成立,则实数a的取值范围是()A0aB03aC3aD3a文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9
4、Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O
5、6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K
6、6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7
7、J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P
8、5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J1
9、0K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6
10、O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8【分值】5【答案】D【易错点】不会去掉绝对值,函数的最值。【考查方向】本题主要考查了含参数的绝对值不等式的恒成立问题。【解题思路】令()3f xxx,依题意,只需求得min()f x即可求得a的取值范围【解析】令3,3()323,3xfxxxxx,则min()3f x,所以min()3af x,即3a,故选 C.4若不等式290 xtx对于任意(0,)x都成立,则t的最大值是()A 0 B-6 C6 D 9【分值】5【答
11、案】C【易错点】不会将变量t 分离出来。【考查方向】本题主要考查了含参数的二次不等式的恒成立问题以及分类变量法。【解题思路】首先根据不等式将t 分离出来,即9txx对任意(0,)x都成立,即min9txx【解 析】不 等 式290 xtx对 于 任 意(0,)x都 成 立 等 价 于9txx对 任 意文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F
12、7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9
13、Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O
14、6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K
15、6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7
16、J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P
17、5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J1
18、0K6F7V4 ZA8Y6O7J9Y8(0,)x都成立因为9926xxxx,所以只需6t即可故C 正确5若关于x的不等式2(2)120 xaxa对任意的 2,2a均成立,则x的取值范围是()A(,1)(3,)B(,5)(5,)C(,5)(3,)D(5,3)【分值】5【答案】C【易错点】不知道讲原不等式转化为关于a 的一次函数。【考查方向】本题主要考查了一元二次不等式恒成立问题,将恒成立问题转化为函数的最值加以解决【解题思路】可将a 视作自变量,则上述问题即可转化为在-2,2内关于 a 的一次函数大于 0 恒成立的问题.解:原不等式转化为2(2)210a xxx在 2,2a时恒成立,设2()(2
19、)21f aa xxx,则()f a在-2,2 上恒大于 0,故有:(2)0(2)0ff即2243050 xxx解得:3155xxxx或或所以35xx或,故选 C.文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z
20、6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F
21、7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9
22、Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O
23、6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K
24、6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7
25、J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8文档编码:CO3P5O6Z6R8 HE2J10K6F7V4 ZA8Y6O7J9Y8填空6若函数()sincos3f xxax的图象始终在直线1y的上方,则a 的取值范围是_【分值】5
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