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第10練指數(shù)與指數(shù)函數(shù)(精練)【A組
在基礎(chǔ)中考查功底】一、單選題1.(2023·全國·學(xué)軍中學(xué)校聯(lián)考二模)已知集合SKIPIF1<0或x≤?2},則SKIPIF1<0(
)A.SKIPIF1<0或SKIPIF1<0 B.SKIPIF1<0或x≤?2}C.SKIPIF1<0或SKIPIF1<0 D.SKIPIF1<0【答案】B【分析】解法一:根據(jù)題意求集合M,進(jìn)而根據(jù)交集運(yùn)算求解;解法二:取特值檢驗(yàn)排除.【詳解】解法一:由題可得SKIPIF1<0或SKIPIF1<0或x≤?2},所以SKIPIF1<0或x≤?2}.故選:B.解法二:由題可得SKIPIF1<0,所以SKIPIF1<0,故排除A、D;又SKIPIF1<0且SKIPIF1<0,所以SKIPIF1<0,故排除C.故選:B.2.(2023·北京朝陽·高三專題練習(xí))“SKIPIF1<0”是“SKIPIF1<0”的(
)A.充分而不必要條件 B.必要而不充分條件C.充分必要條件 D.既不充分也不必要條件【答案】A【分析】根據(jù)充分條件和必要條件的定義,結(jié)合指數(shù)函數(shù)的單調(diào)性即可得出答案.【詳解】因?yàn)橹笖?shù)函數(shù)SKIPIF1<0單調(diào)遞增,由SKIPIF1<0可得:SKIPIF1<0,充分性成立,當(dāng)SKIPIF1<0時,SKIPIF1<0,但不一定SKIPIF1<0,必要性不成立,故選:A3.(2023·江西南昌·南昌縣蓮塘第一中學(xué)校聯(lián)考二模)為了預(yù)防某種病毒,某學(xué)校需要通過噴灑藥物對教室進(jìn)行全面消毒.出于對學(xué)生身體健康的考慮,相關(guān)部門規(guī)定空氣中這種藥物的濃度不超過0.25毫克/立方米時,學(xué)生方可進(jìn)入教室.已知從噴灑藥物開始,教室內(nèi)部的藥物濃度y(毫克/立方米)與時間t(分鐘)之間的函數(shù)關(guān)系為SKIPIF1<0,函數(shù)的圖像如圖所示.如果早上7:30就有學(xué)生進(jìn)入教室,那么開始噴灑藥物的時間最遲是(
)A.7:00 B.6:40 C.6:30 D.6:00【答案】A【分析】函數(shù)的圖像過點(diǎn)SKIPIF1<0,代入函數(shù)的解析式求得未知系數(shù)a,解函數(shù)不等式即可.【詳解】根據(jù)函數(shù)的圖像,可得函數(shù)的圖像過點(diǎn)SKIPIF1<0,由函數(shù)圖像連續(xù),代入函數(shù)的解析式,可得SKIPIF1<0,解得SKIPIF1<0,所以SKIPIF1<0,令SKIPIF1<0,可得SKIPIF1<0或SKIPIF1<0,解得SKIPIF1<0或SKIPIF1<0.所以如果7:30學(xué)生進(jìn)入教室,那么開始噴灑藥物的時間最遲是7:00.故選:A.4.(2023·陜西商洛·統(tǒng)考二模)函數(shù)SKIPIF1<0的部分圖象大致是(
)A. B.C. D.【答案】C【分析】奇偶性定義判斷函數(shù)奇偶性,結(jié)合SKIPIF1<0上函數(shù)符號,應(yīng)用排除法即可得答案.【詳解】因?yàn)镾KIPIF1<0,所以SKIPIF1<0且定義域?yàn)镽,所以SKIPIF1<0是奇函數(shù),則SKIPIF1<0的圖象關(guān)于原點(diǎn)對稱,排除A、B.當(dāng)SKIPIF1<0時,SKIPIF1<0,排除D.故選:C5.(2023秋·吉林遼源·高三校聯(lián)考期末)已知函數(shù)SKIPIF1<0,若SKIPIF1<0,則實(shí)數(shù)a的取值范圍是(
)A.SKIPIF1<0 B.SKIPIF1<0 C.SKIPIF1<0 D.SKIPIF1<0【答案】C【分析】構(gòu)造函數(shù)SKIPIF1<0,研究函數(shù)SKIPIF1<0的單調(diào)性與奇偶性,利用函數(shù)性質(zhì)解不等式.【詳解】令SKIPIF1<0,定義域?yàn)镾KIPIF1<0,且SKIPIF1<0,所以函數(shù)SKIPIF1<0為定義域內(nèi)的奇函數(shù),且在SKIPIF1<0上單調(diào)遞增;則SKIPIF1<0,則SKIPIF1<0,即SKIPIF1<0,即SKIPIF1<0,又因?yàn)镾KIPIF1<0為定義域內(nèi)的奇函數(shù),所以SKIPIF1<0,又因?yàn)镾KIPIF1<0在SKIPIF1<0上單調(diào)遞增,所以SKIPIF1<0,解得SKIPIF1<0或SKIPIF1<0,故實(shí)數(shù)a的取值范圍是SKIPIF1<0.故選:C6.(2023秋·湖南長沙·高三??茧A段練習(xí))設(shè)SKIPIF1<0,用SKIPIF1<0表示不超過SKIPIF1<0的最大整數(shù),則SKIPIF1<0稱取整函數(shù),例如:SKIPIF1<0,SKIPIF1<0已知SKIPIF1<0則函數(shù)SKIPIF1<0的值域?yàn)椋?/p>
)A.SKIPIF1<0 B.SKIPIF1<0 C.SKIPIF1<0 D.SKIPIF1<0【答案】D【分析】分離常數(shù)得SKIPIF1<0,進(jìn)而求得SKIPIF1<0,從而可得答案.【詳解】SKIPIF1<0SKIPIF1<0SKIPIF1<0,SKIPIF1<0SKIPIF1<0,SKIPIF1<0SKIPIF1<0,SKIPIF1<0SKIPIF1<0,當(dāng)SKIPIF1<0當(dāng)SKIPIF1<0.故選:D二、多選題7.(2023春·重慶渝中·高三重慶巴蜀中學(xué)??茧A段練習(xí))若SKIPIF1<0,其中SKIPIF1<0為自然對數(shù)的底數(shù),則下列命題正確的是(
)A.SKIPIF1<0在SKIPIF1<0上單調(diào)遞增 B.SKIPIF1<0在SKIPIF1<0上單調(diào)遞減C.SKIPIF1<0的圖象關(guān)于直線SKIPIF1<0對稱 D.SKIPIF1<0的圖象關(guān)于點(diǎn)SKIPIF1<0中心對稱【答案】BC【分析】根據(jù)復(fù)合函數(shù)的單調(diào)性判斷A、B,根據(jù)奇偶性的定義判斷函數(shù)為偶函數(shù),即可判斷C、D.【詳解】因?yàn)镾KIPIF1<0在SKIPIF1<0上單調(diào)遞減,在SKIPIF1<0上單調(diào)遞增,SKIPIF1<0在定義域SKIPIF1<0上單調(diào)遞增,所以SKIPIF1<0在SKIPIF1<0上單調(diào)遞減,在SKIPIF1<0上單調(diào)遞增,故A錯誤,B正確;又SKIPIF1<0,所以SKIPIF1<0為偶函數(shù),函數(shù)圖象關(guān)于SKIPIF1<0軸對稱,即關(guān)于直線SKIPIF1<0對稱,故C正確,D錯誤;故選:BC8.(2023春·云南昭通·高三??茧A段練習(xí))已知函數(shù)SKIPIF1<0,下列說法中正確的是(
)A.SKIPIF1<0不是周期函數(shù) B.SKIPIF1<0在(0,SKIPIF1<0)上是單調(diào)遞增函數(shù)C.SKIPIF1<0在(0,SKIPIF1<0)內(nèi)有且只有一個零點(diǎn) D.SKIPIF1<0關(guān)于點(diǎn)(SKIPIF1<0,0)對稱【答案】BCD【分析】根據(jù)周期函數(shù)的定義、指數(shù)函數(shù)、正弦函數(shù)、余弦函數(shù)的單調(diào)性,結(jié)合零點(diǎn)定義和點(diǎn)對稱的性質(zhì)逐一判斷即可.【詳解】∵SKIPIF1<0,∴SKIPIF1<0是周期函數(shù),A錯誤;當(dāng)x∈(0,SKIPIF1<0)時,sinx是增函數(shù),cosx是減函數(shù),∴SKIPIF1<0是增函數(shù),SKIPIF1<0是減函數(shù),SKIPIF1<0是增函數(shù),∴SKIPIF1<0是增函數(shù),B對;由SKIPIF1<0得sinx=cosx,因?yàn)镾KIPIF1<0,所以有SKIPIF1<0,C對;∵SKIPIF1<0,∴SKIPIF1<0關(guān)于點(diǎn)(SKIPIF1<0,0)對稱,D對,故選:BCD.三、填空題9.(2023·全國·高三專題練習(xí))SKIPIF1<0________.【答案】19【分析】根據(jù)指數(shù)冪的運(yùn)算性質(zhì)即可求解.【詳解】SKIPIF1<0SKIPIF1<0.故答案為:1910.(2023·全國·模擬預(yù)測)已知函數(shù)SKIPIF1<0,則SKIPIF1<0______.【答案】4【分析】根據(jù)函數(shù)的奇偶性,結(jié)合代入法進(jìn)行求解即可.【詳解】設(shè)SKIPIF1<0,SKIPIF1<0為偶函數(shù),所以SKIPIF1<0.故答案為:SKIPIF1<011.(2023·全國·高三專題練習(xí))函數(shù)SKIPIF1<0的值域?yàn)開_______.【答案】SKIPIF1<0【分析】根據(jù)二次函數(shù)的圖像性質(zhì)和指數(shù)函數(shù)的性質(zhì)求解.【詳解】因?yàn)楹瘮?shù)SKIPIF1<0的對稱軸為SKIPIF1<0,所以SKIPIF1<0,又因?yàn)镾KIPIF1<0,所以SKIPIF1<0,所以SKIPIF1<0,所以SKIPIF1<0,故答案為:SKIPIF1<0.12.(2023·全國·高三專題練習(xí))寫出一個同時滿足下列三個性質(zhì)的函數(shù)SKIPIF1<0__________.①若SKIPIF1<0,則SKIPIF1<0;②SKIPIF1<0;③SKIPIF1<0在SKIPIF1<0上單調(diào)遞減.【答案】SKIPIF1<0(答案不唯一)【分析】根據(jù)函數(shù)的三個性質(zhì),列出符合條件的函數(shù)即可.【詳解】比如SKIPIF1<0,SKIPIF1<0,故SKIPIF1<0,又SKIPIF1<0,也即SKIPIF1<0成立,又SKIPIF1<0在SKIPIF1<0上單調(diào)遞減.故答案為:SKIPIF1<0.13.(2023春·河南鄭州·高三??茧A段練習(xí))已知函數(shù)SKIPIF1<0,若實(shí)數(shù)a,SKIPIF1<0滿足SKIPIF1<0且SKIPIF1<0,則SKIPIF1<0___________.【答案】SKIPIF1<0【分析】根據(jù)指數(shù)式的運(yùn)算和指數(shù)函數(shù)函數(shù)值的運(yùn)算求解.【詳解】SKIPIF1<0,由SKIPIF1<0,可得SKIPIF1<0所以SKIPIF1<0①,因?yàn)镾KIPIF1<0,所以SKIPIF1<0,解得SKIPIF1<0②,聯(lián)立①②解得SKIPIF1<0SKIPIF1<0,故答案為:SKIPIF1<0.14.(2023·全國·高三練習(xí))若關(guān)于SKIPIF1<0的方程SKIPIF1<0有實(shí)根,則實(shí)數(shù)SKIPIF1<0的取值范圍為______.【答案】SKIPIF1<0【分析】方程SKIPIF1<0有實(shí)根可轉(zhuǎn)化為SKIPIF1<0在SKIPIF1<0上有解,根據(jù)SKIPIF1<0的范圍求解SKIPIF1<0的取值范圍即可.【詳解】方程SKIPIF1<0有實(shí)根,所以SKIPIF1<0有實(shí)根,令SKIPIF1<0,因?yàn)镾KIPIF1<0,所以SKIPIF1<0,所以SKIPIF1<0在SKIPIF1<0上有解,又因?yàn)楫?dāng)SKIPIF1<0時SKIPIF1<0,所以SKIPIF1<0,故答案為:SKIPIF1<0四、解答題15.(2023·全國·高三專題練習(xí))已知向量SKIPIF1<0,SKIPIF1<0,若SKIPIF1<0,求:(1)實(shí)數(shù)m的取值范圍;(2)函數(shù)SKIPIF1<0定義域.【答案】(1)SKIPIF1<0;(2)SKIPIF1<0.【分析】(1)根據(jù)數(shù)量積的坐標(biāo)表示,求解不等式即可得出答案;(2)根據(jù)(1)中m的取值范圍,再運(yùn)用指數(shù)函數(shù)的單調(diào)性求解定義域即可.【詳解】(1)由題意得,SKIPIF1<0,SKIPIF1<0,即m的取值范圍為SKIPIF1<0;(2)由題意知SKIPIF1<0,即SKIPIF1<0,由(1)知SKIPIF1<0,根據(jù)指數(shù)函數(shù)的單調(diào)性得:SKIPIF1<0,解得SKIPIF1<0或SKIPIF1<0,所以函數(shù)SKIPIF1<0的定義域?yàn)镾KIPIF1<0.16.(2023·全國·高三專題練習(xí))已知a>0,且a≠1,若函數(shù)y=|ax-2|與y=3a的圖象有兩個交點(diǎn),求實(shí)數(shù)a的取值范圍.【答案】SKIPIF1<0【分析】討論0<a<1或a>1,作出函數(shù)y=|a-2|與y=3a的圖象,由數(shù)形結(jié)合即可求解.【詳解】①當(dāng)0<a<1時,在同一平面直角坐標(biāo)系中作出函數(shù)y=|a-2|與y=3a的圖象如圖1.若直線y=3a與函數(shù)y=|a-2|(0<a<1)的圖象有兩個交點(diǎn),則由圖象可知0<3a<2,所以0<a<SKIPIF1<0.②當(dāng)a>1時,在同一平面直角坐標(biāo)系中作出函數(shù)y=|a-2|與y=3a的圖象如圖2.若直線y=3a與函數(shù)y=|a-2|(a>1)的圖象有兩個交點(diǎn),則由圖象可知0<3a<2,此時無解.所以實(shí)數(shù)a的取值范圍是SKIPIF1<0.【B組
在綜合中考查能力】一、單選題1.(2023·甘肅武威·統(tǒng)考三模)函數(shù)SKIPIF1<0的圖象大致是(
)A. B. C. D.【答案】D【分析】SKIPIF1<0,排除BC,當(dāng)SKIPIF1<0時,SKIPIF1<0,當(dāng)SKIPIF1<0時,SKIPIF1<0,A不滿足,排除,得到答案.【詳解】SKIPIF1<0,排除BC;當(dāng)SKIPIF1<0時,SKIPIF1<0,當(dāng)SKIPIF1<0時,SKIPIF1<0,A不滿足,排除.故選:D2.(2023·四川綿陽·統(tǒng)考模擬預(yù)測)設(shè)函數(shù)SKIPIF1<0在定義域SKIPIF1<0上滿足SKIPIF1<0,若SKIPIF1<0在SKIPIF1<0上是減函數(shù),且SKIPIF1<0,則不等式SKIPIF1<0的解集為(
)A.SKIPIF1<0 B.SKIPIF1<0 C.SKIPIF1<0 D.SKIPIF1<0【答案】A【分析】根據(jù)題意可得函數(shù)SKIPIF1<0在定義域SKIPIF1<0上奇函數(shù),進(jìn)而可得SKIPIF1<0在SKIPIF1<0上是減函數(shù),根據(jù)題意結(jié)合單調(diào)性解不等式即可.【詳解】∵SKIPIF1<0,即SKIPIF1<0,故函數(shù)SKIPIF1<0在定義域SKIPIF1<0上奇函數(shù),若SKIPIF1<0在SKIPIF1<0上是減函數(shù),則SKIPIF1<0在SKIPIF1<0上是減函數(shù),∵SKIPIF1<0,且SKIPIF1<0,若SKIPIF1<0,則SKIPIF1<0,解得SKIPIF1<0,故不等式SKIPIF1<0的解集為SKIPIF1<0.故選:A.3.(2023·湖南益陽·統(tǒng)考模擬預(yù)測)已知SKIPIF1<0,SKIPIF1<0,SKIPIF1<0,則下列結(jié)論正確的是(
)A.SKIPIF1<0 B.SKIPIF1<0 C.SKIPIF1<0 D.SKIPIF1<0【答案】C【分析】作商與1比較進(jìn)而比較指數(shù)冪的大小,再構(gòu)造函數(shù)SKIPIF1<0,根據(jù)單調(diào)性比較函數(shù)值大小即可.【詳解】因?yàn)镾KIPIF1<0,SKIPIF1<0,所以SKIPIF1<0,所以SKIPIF1<0,因?yàn)镾KIPIF1<0,令設(shè)SKIPIF1<0,令SKIPIF1<0,可得SKIPIF1<0,且SKIPIF1<0時,SKIPIF1<0,所以SKIPIF1<0,即SKIPIF1<0,可得SKIPIF1<0,即SKIPIF1<0所以SKIPIF1<0故選:SKIPIF1<04.(2023·全國·高三專題練習(xí))已知函數(shù)SKIPIF1<0的定義域?yàn)镾KIPIF1<0,SKIPIF1<0是偶函數(shù),SKIPIF1<0是奇函數(shù),則SKIPIF1<0的最小值為(
)A.SKIPIF1<0 B.SKIPIF1<0 C.SKIPIF1<0 D.SKIPIF1<0【答案】B【分析】利用函數(shù)奇偶性的定義可求得函數(shù)SKIPIF1<0的解析式,再利用基本不等式可求得SKIPIF1<0的最小值.【詳解】因?yàn)楹瘮?shù)SKIPIF1<0為偶函數(shù),則SKIPIF1<0,即SKIPIF1<0,①又因?yàn)楹瘮?shù)SKIPIF1<0為奇函數(shù),則SKIPIF1<0,即SKIPIF1<0,②聯(lián)立①②可得SKIPIF1<0,由基本不等式可得SKIPIF1<0,當(dāng)且僅當(dāng)SKIPIF1<0時,即當(dāng)SKIPIF1<0時,等號成立,故函數(shù)SKIPIF1<0的最小值為SKIPIF1<0.故選:B.5.(2023·全國·高三專題練習(xí))已知SKIPIF1<0,SKIPIF1<0,SKIPIF1<0則實(shí)數(shù)a,b,c的大小關(guān)系為(
)A.c>a>b B.a(chǎn)>b>cC.a(chǎn)>c>b D.c>b>a【答案】A【分析】先利用作商法比較a,b的大小,再借助中間值“0.5”得到SKIPIF1<0,得到a<c,即可得到結(jié)果.【詳解】易知SKIPIF1<0,所以SKIPIF1<0,因?yàn)镾KIPIF1<0由SKIPIF1<0得SKIPIF1<0所以SKIPIF1<0,所以a<c.所以實(shí)數(shù)a,b,c的大小關(guān)系為c>a>b.故選:A.6.(2023·貴州·統(tǒng)考模擬預(yù)測)若函數(shù)SKIPIF1<0的最小值為SKIPIF1<0,則SKIPIF1<0(
)A.SKIPIF1<0 B.SKIPIF1<0 C.SKIPIF1<0 D.SKIPIF1<0【答案】C【分析】根據(jù)x的范圍分類討論去掉SKIPIF1<0的絕對值符號,再根據(jù)二次函數(shù)的性質(zhì)和f(x)的最小值即可求出關(guān)于a的方程SKIPIF1<0,令SKIPIF1<0,根據(jù)g(a)的單調(diào)性即可求出a的范圍.【詳解】當(dāng)SKIPIF1<0時,SKIPIF1<0,當(dāng)SKIPIF1<0時,SKIPIF1<0,∵SKIPIF1<0,∴SKIPIF1<0的最小值為SKIPIF1<0,∴SKIPIF1<0,即SKIPIF1<0,設(shè)SKIPIF1<0,則SKIPIF1<0是R上的增函數(shù),∵SKIPIF1<0,SKIPIF1<0,∴SKIPIF1<0.故選:C.二、多選題7.(2023·山東青島·統(tǒng)考模擬預(yù)測)已知函數(shù)SKIPIF1<0,則(
)A.當(dāng)SKIPIF1<0時,SKIPIF1<0 B.當(dāng)SKIPIF1<0時,SKIPIF1<0C.當(dāng)SKIPIF1<0時,SKIPIF1<0 D.當(dāng)SKIPIF1<0時,方程SKIPIF1<0有兩個解【答案】AC【分析】結(jié)合SKIPIF1<0在定義域內(nèi)單調(diào)性,判斷A;利用導(dǎo)數(shù)判斷函數(shù)SKIPIF1<0在SKIPIF1<0單調(diào)性,由此判斷B;判斷函數(shù)SKIPIF1<0,在SKIPIF1<0上的單調(diào)性,由此判斷C;,舉反例判斷D.【詳解】SKIPIF1<0在定義域內(nèi)單調(diào)遞增,所以當(dāng)SKIPIF1<0時,SKIPIF1<0,即當(dāng)SKIPIF1<0時,SKIPIF1<0,所以SKIPIF1<0,故A正確;當(dāng)SKIPIF1<0時,要證明SKIPIF1<0,只需證明SKIPIF1<0,故考慮構(gòu)造函數(shù)SKIPIF1<0,則SKIPIF1<0,當(dāng)SKIPIF1<0時,SKIPIF1<0,函數(shù)SKIPIF1<0在SKIPIF1<0單調(diào)遞增,所以當(dāng)SKIPIF1<0時,SKIPIF1<0,即SKIPIF1<0,所以B錯誤;設(shè)SKIPIF1<0,則SKIPIF1<0,當(dāng)SKIPIF1<0時,SKIPIF1<0,函數(shù)SKIPIF1<0在SKIPIF1<0上單調(diào)遞減,當(dāng)SKIPIF1<0時,SKIPIF1<0,函數(shù)SKIPIF1<0在SKIPIF1<0上單調(diào)遞增,當(dāng)SKIPIF1<0時,SKIPIF1<0,即SKIPIF1<0,C正確;取SKIPIF1<0可得,方程SKIPIF1<0等價于SKIPIF1<0,解得SKIPIF1<0,即SKIPIF1<0時,方程SKIPIF1<0只有一個解,D錯誤.故選:AC.8.(2023·全國·模擬預(yù)測)已知SKIPIF1<0,SKIPIF1<0為SKIPIF1<0導(dǎo)函數(shù),SKIPIF1<0,SKIPIF1<0,則下列說法正確的是(
)A.SKIPIF1<0為偶函數(shù) B.當(dāng)SKIPIF1<0且SKIPIF1<0時,SKIPIF1<0恒成立C.SKIPIF1<0的值域?yàn)镾KIPIF1<0 D.SKIPIF1<0與曲線SKIPIF1<0無交點(diǎn)【答案】AD【分析】對A,由偶函數(shù)定義判斷;對B,結(jié)合指數(shù)函數(shù)的非負(fù)性,判斷存在SKIPIF1<0即可;對C,化簡SKIPIF1<0,求指數(shù)函數(shù)復(fù)合型函數(shù)的值域即可.對D,聯(lián)立兩曲線,判斷方程的解即可.【詳解】對A,SKIPIF1<0,SKIPIF1<0,∴SKIPIF1<0為偶函數(shù),A對;對B,SKIPIF1<0,因?yàn)镾KIPIF1<0,所以當(dāng)SKIPIF1<0,SKIPIF1<0,B錯;對C,由SKIPIF1<0可得SKIPIF1<0,∵SKIPIF1<0,∴SKIPIF1<0,∴SKIPIF1<0,C錯;對D,由SKIPIF1<0,方程無解,∴SKIPIF1<0與曲線SKIPIF1<0無交點(diǎn),D對.故選:AD三、填空題9.(2023·全國·高三專題練習(xí))已知函數(shù)SKIPIF1<0所過的定點(diǎn)在一次函數(shù)SKIPIF1<0的圖像上,則SKIPIF1<0的最小值為__________.【答案】SKIPIF1<0【分析】由指數(shù)函數(shù)性質(zhì)與基本不等式求解,【詳解】令SKIPIF1<0得SKIPIF1<0,由題意得SKIPIF1<0過的定點(diǎn)為SKIPIF1<0,則SKIPIF1<0,SKIPIF1<0SKIPIF1<0,當(dāng)且僅當(dāng)SKIPIF1<0即SKIPIF1<0時等號成立,故SKIPIF1<0的最小值為SKIPIF1<0,故答案為:SKIPIF1<010.(2023·全國·高三專題練習(xí))已知函數(shù)SKIPIF1<0(SKIPIF1<0且SKIPIF1<0)在區(qū)間SKIPIF1<0上是減函數(shù),則實(shí)數(shù)SKIPIF1<0的取值范圍是________.【答案】SKIPIF1<0【分析】令SKIPIF1<0,則SKIPIF1<0,則由題意可得SKIPIF1<0在區(qū)間SKIPIF1<0上為減函數(shù),SKIPIF1<0為增函數(shù),則SKIPIF1<0,所以得SKIPIF1<0對任意的SKIPIF1<0恒成立,從而可得SKIPIF1<0,進(jìn)而可求出結(jié)果.【詳解】令SKIPIF1<0,則SKIPIF1<0,由于SKIPIF1<0且SKIPIF1<0,內(nèi)層函數(shù)SKIPIF1<0在區(qū)間SKIPIF1<0上為減函數(shù),所以外層函數(shù)SKIPIF1<0為增函數(shù),所以SKIPIF1<0.由題意可知,不等式SKIPIF1<0對任意的SKIPIF1<0恒成立,所以SKIPIF1<0,解得SKIPIF1<0.綜上所述,實(shí)數(shù)SKIPIF1<0的取值范圍是SKIPIF1<0.故答案為:SKIPIF1<011.(2023·北京朝陽·高三專題練習(xí))若函數(shù)SKIPIF1<0的值域?yàn)镾KIPIF1<0,則實(shí)數(shù)SKIPIF1<0的一個取值可以為___________.【答案】1【分析】考察函數(shù)SKIPIF1<0的圖像,就是先把SKIPIF1<0向上或向下平移SKIPIF1<0個單位(取決于SKIPIF1<0的符號),如果圖像存在小于零的部分,則再把小于零的部分以x軸為對稱軸翻折上去,最后再把整個圖像向下平移一個單位.【詳解】如果SKIPIF1<0,SKIPIF1<0SKIPIF1<0,其值域?yàn)镾KIPIF1<0,SKIPIF1<0,不符合題意;如果SKIPIF1<0,當(dāng)SKIPIF1<0時,SKIPIF1<0,SKIPIF1<0就是把函數(shù)SKIPIF1<0的部分以x軸為對稱軸翻折上去,∴此時SKIPIF1<0的最小值為0,SKIPIF1<0的最小值為-1,值域?yàn)镾KIPIF1<0,所以SKIPIF1<0,不妨取SKIPIF1<0;故答案為:1.12.(2023·全國·高三專題練習(xí))已知函數(shù)SKIPIF1<0是定義在R上的奇函數(shù),若不等式SKIPIF1<0對任意的SKIPIF1<0恒成立,則實(shí)數(shù)m的取值范圍是__________.【答案】SKIPIF1<0【分析】利用函數(shù)的奇偶性和單調(diào)性可得不等式SKIPIF1<0在SKIPIF1<0恒成立,換元法討論函數(shù)在給定區(qū)間的單調(diào)性和最值,結(jié)合分類討論即可求SKIPIF1<0的范圍.【詳解】因?yàn)楹瘮?shù)SKIPIF1<0是定義在R上的奇函數(shù),所以SKIPIF1<0解得SKIPIF1<0,此時SKIPIF1<0,SKIPIF1<0函數(shù)為奇函數(shù),滿足題意,所以SKIPIF1<0,因?yàn)镾KIPIF1<0在R上單調(diào)遞增,所以SKIPIF1<0在R上單調(diào)遞減,所以SKIPIF1<0在R上單調(diào)遞增,所以由SKIPIF1<0可得,SKIPIF1<0即SKIPIF1<0,所以SKIPIF1<0即SKIPIF1<0在SKIPIF1<0恒成立,令SKIPIF1<0,即SKIPIF1<0,當(dāng)SKIPIF1<0時,SKIPIF1<0,不等式可化為SKIPIF1<0,令SKIPIF1<0,SKIPIF1<0單調(diào)遞減,所以SKIPIF1<0,所以SKIPIF1<0;當(dāng)SKIPIF1<0時,SKIPIF1<0,不等式SKIPIF1<0顯然成立;當(dāng)SKIPIF1<0時,SKIPIF1<0,不等式可化為SKIPIF1<0,令SKIPIF1<0,SKIPIF1<0單調(diào)遞減,所以SKIPIF1<0,所以SKIPIF1<0;綜上,SKIPIF1<0,故答案為:SKIPIF1<0.四、解答題13.(2023·全國·高三專題練習(xí))設(shè)定義在SKIPIF1<0上的偶函數(shù)SKIPIF1<0和奇函數(shù)SKIPIF1<0滿足SKIPIF1<0(其中SKIPIF1<0),且SKIPIF1<0.(1)求函數(shù)SKIPIF1<0和SKIPIF1<0的解析式;(2)若SKIPIF1<0的最小值為SKIPIF1<0,求實(shí)數(shù)SKIPIF1<0的值.【答案】(1)SKIPIF1<0,SKIPIF1<0(2)SKIPIF1<0【分析】(1)由已知可得SKIPIF1<0,結(jié)合奇函數(shù)和偶函數(shù)的性質(zhì)變形求解即可;(2)令SKIPIF1<0,函數(shù)SKIPIF1<0可化為關(guān)于SKIPIF1<0的函數(shù),結(jié)合二次函數(shù)性質(zhì)求其最小值,列方程求SKIPIF1<0的值.【詳解】(1)因?yàn)镾KIPIF1<0,所以SKIPIF1<0,因?yàn)楹瘮?shù)SKIPIF1<0為偶函數(shù),函數(shù)SKIPIF1<0為奇函數(shù),所以SKIPIF1<0,即SKIPIF1<0,所以SKIPIF1<0,SKIPIF1<0,又SKIPIF1<0,SKIPIF1<0,所以SKIPIF1<0或SKIPIF1<0(舍),從而SKIPIF1<0,SKIPIF1<0.(2)因?yàn)镾KIPIF1<0,SKIPIF1<0,SKIPIF1<0,所以SKIPIF1<0,令SKIPIF1<0,則SKIPIF1<0:所以SKIPIF1<0,因?yàn)镾KIPIF1<0,當(dāng)且僅當(dāng)SKIPIF1<0時取等號,SKIPIF1<0,所以SKIPIF1<0,所以SKIPIF1<0.【C組
在創(chuàng)新中考查思維】一、單選題1.(2023·浙江溫州·統(tǒng)考三模)已知函數(shù)SKIPIF1<0,存在實(shí)數(shù)SKIPIF1<0使得SKIPIF1<0成立,若正整數(shù)SKIPIF1<0的最大值為6,則SKIPIF1<0的取值范圍為(
)A.SKIPIF1<0 B.SKIPIF1<0C.SKIPIF1<0 D.SKIPIF1<0【答案】C【分析】分類討論SKIPIF1<0的值域,然后根據(jù)值域端點(diǎn)的倍數(shù)關(guān)系可解.【詳解】記SKIPIF1<0因?yàn)镾KIPIF1<0,所以SKIPIF1<0,所以SKIPIF1<0當(dāng)SKIPIF1<0時,SKIPIF1<0,所以SKIPIF1<0顯然存在任意正整數(shù)SKIPIF1<0,使得SKIPIF1<0成立;當(dāng)SKIPIF1<0時,SKIPIF1<0,所以SKIPIF1<0要使正整數(shù)SKIPIF1<0的最大值為6,則SKIPIF1<0,解得SKIPIF1<0;當(dāng)SKIPIF1<0時,SKIPIF1<0,所以SKIPIF1<0顯然存在任意正整數(shù)SKIPIF1<0,使得SKIPIF1<0成立;當(dāng)SKIPIF1<0時,SKIPIF1<0,所以SKIPIF1<0要使正整數(shù)SKIPIF1<0的最大值為6,則SKIPIF1<0,解得SKIPIF1<0綜上,SKIPIF1<0的取值范圍為SKIPIF1<0故選:C2.(2023·北京朝陽·二模)已知函數(shù)SKIPIF1<0是SKIPIF1<0上的奇函數(shù),當(dāng)SKIPIF1<0時,SKIPIF1<0.若關(guān)于x的方程SKIPIF1<0有且僅有兩個不相等的實(shí)數(shù)解則實(shí)數(shù)m的取值范圍是(
)A.SKIPIF1<0 B.SKIPIF1<0 C.SKIPIF1<0 D.SKIPIF1<0【答案】C【分析】利用奇函數(shù)性質(zhì)求分段函數(shù)解析式,根據(jù)指數(shù)函數(shù)性質(zhì)畫出SKIPIF1<0函數(shù)圖象,數(shù)形結(jié)合判斷不同值域范圍的函數(shù)值對應(yīng)自變量的個數(shù),再由SKIPIF1<0有兩個解,對應(yīng)SKIPIF1<0的解的個數(shù)確定SKIPIF1<0范圍,進(jìn)而求m的范圍.【詳解】由題設(shè)SKIPIF1<0,若SKIPIF1<0,則SKIPIF1<0,所以SKIPIF1<0,值域?yàn)镽,函數(shù)圖象如下:當(dāng)SKIPIF1<0時,只有一個SKIPIF1<0與之對應(yīng);當(dāng)SKIPIF1<0時,有兩個對應(yīng)自變量,記為SKIPIF1<0,則SKIPIF1<0;當(dāng)SKIPIF1<0時,有三個對應(yīng)自變量且SKIPIF1<0;當(dāng)SKIPIF1<0時,有兩個對應(yīng)自變量,記為SKIPIF1<0,則SKIPIF1<0;當(dāng)SKIPIF1<0時,有一個SKIPIF1<0與之對應(yīng);令SKIPIF1<0,則SKIPIF1<0,要使SKIPIF1<0有且僅有兩個不相等的實(shí)數(shù)解,若SKIPIF1<0有三個解,則SKIPIF1<0,此時SKIPIF1<0有5個解,不滿足;若SKIPIF1<0有兩個解SKIPIF1<0且SKIPIF1<0,此時SKIPIF1<0和SKIPIF1<0各有一個解,結(jié)合圖象知,不存在這樣的SKIPIF1<0,故不存在對應(yīng)的m;若SKIPIF1<0有一個解SKIPIF1<0,則SKIPIF1<0有兩個解,此時SKIPIF1<0,所以對應(yīng)的SKIPIF1<0,綜上,SKIPIF1<0.故選:C.二、多選題3.(2023·全國·高三專題練習(xí))函數(shù)SKIPIF1<0的定義域?yàn)镾KIPIF1<0,值域?yàn)镾KIPIF1<0,下列結(jié)論中一定成立的結(jié)論的序號是(
)A.SKIPIF1<0 B.SKIPIF1<0 C.SKIPIF1<0 D.SKIPIF1<0【答案】ACD【分析】先研究值域?yàn)镾KIPIF1<0時函數(shù)的定義域,再研究使得值域?yàn)镾KIPIF1<0得函數(shù)的最小值的自變量的取值集合,研究函數(shù)值取1,2時對應(yīng)的自變量的取值,由此可判斷各個選項(xiàng).【詳解】由于SKIPIF1<0,SKIPIF1<0,SKIPIF1<0,SKIPIF1<0,SKIPIF1<0,即函數(shù)SKIPIF1<0的定義域?yàn)镾KIPIF1<0當(dāng)函數(shù)的最小值為1時,僅有SKIPIF1<0滿足,所以SKIPIF1<0,故D正確;當(dāng)函數(shù)的最大值為2時,僅有SKIPIF1<0滿足,所以SKIPIF1<0,故C正確;即當(dāng)SKIPIF1<0時,函數(shù)的值域?yàn)镾KIPIF1<0,故SKIPIF1<0,故SKIPIF1<0不一定正確,故A正確,B錯誤;故選:ACD【點(diǎn)睛】關(guān)鍵點(diǎn)睛:本題考查函數(shù)的定義域及其求法,解題的關(guān)鍵是通過函數(shù)的值域求出函數(shù)的定義域,再利用元素與集合關(guān)系的判斷,集合的包含關(guān)系判斷,考查了學(xué)生的邏輯推理與轉(zhuǎn)化能力,屬于基礎(chǔ)題.三、填空題4.(2023·北京東城·統(tǒng)考二模)定義在區(qū)間SKIPIF1<0上的函數(shù)SKIPIF1<0的圖象是一條連續(xù)不斷的曲線,SKIPIF1<0在區(qū)間SKIPIF1<0上單調(diào)遞增,在區(qū)間SKIPIF1<0上單調(diào)遞減,SKIPIF1<0給出下列四個結(jié)論:①若SKIPIF1<0為遞增數(shù)列,則SKIPIF1<0存在最大值;②若SKIPIF1<0為遞增數(shù)列,則SKIPIF1<0存在最小值;③若SKIPIF1<0,且SKIPIF1<0存在最小值,則SKIPIF1<0存在最小值;④若SKIPIF1<0,且SKIPIF1<0存在最大值,則SKIPIF1<0存在最大值.其中所有錯誤結(jié)論的序號有_______.【答案】①③④【分析】結(jié)合函數(shù)的單調(diào)性判斷最值,即可判斷①②,利用取反例,判斷③④.【詳解】①由條件可知,函數(shù)SKIPIF1<0在區(qū)間SKIPIF1<0上單調(diào)遞增,在區(qū)間SKIPIF1<0上單調(diào)遞減,SKIPIF1<0那么在區(qū)間SKIPIF1<0,函數(shù)的最大值是SKIPIF1<0,若數(shù)列SKIPIF1<0為遞增數(shù)列,則函數(shù)SKIPIF1<0不存在最大值,故①錯誤;②由條件可知,函數(shù)SKIPIF1<0在區(qū)間SKIPIF1<0上單調(diào)遞增,在區(qū)間SKIPIF1<0上單調(diào)遞減,若SKIPIF1<0為遞增數(shù)列,那么在區(qū)間SKIPIF1<0的最小值是SKIPIF1<0,且SKIPIF1<0為遞增數(shù)列,所以函數(shù)SKIPIF1<0在區(qū)間SKIPIF1<0的最小值是SKIPIF1<0,故②正確;③若SKIPIF1<0,取SKIPIF1<0,SKIPIF1<0,則SKIPIF1<0,存在最小值,但此時SKIPIF1<0的最小值是SKIPIF1<0的最小值,函數(shù)單調(diào)遞減,無最小值,故③錯誤;④若SKIPIF1<0,取SKIPIF1<0,則SKIPIF1<0恒成立,則SKIPIF1<0有最大值,但SKIPIF1<0的最大值是SKIPIF1<0的最大值,函數(shù)單調(diào)遞增,無最大值,故④錯誤.故答案為:①③④5.(2023·全國·模擬預(yù)測)已知SKIPIF1<0,若存在SKIPIF1<0,使得SKIPIF1<0,則SKIPIF1<0的取值范圍為___________.【答案】SKIPIF1<0【分析】先討論SKIPIF1<0、SKIPIF1<0與1的大小關(guān)系確定SKIPIF1<0、SKIPIF1<0,進(jìn)而確定SKIPIF1<0的取值范圍,再結(jié)合函數(shù)的單調(diào)性進(jìn)行求解.【詳解】①當(dāng)SKIPIF1<0時,則SKIPIF1<0,SKIPIF1<0,又由SKIPIF1<0,得SKIPIF1<0,所以SKIPIF1<0,則SKIPIF1<0;②當(dāng)SKIPIF1<0時,因?yàn)镾KIPIF1<0,SKIPIF1<0,所以不存在SKIPIF1<0,使得SKIPIF1<0;③當(dāng)SKIPIF1<0
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