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江西省2024年初中学业水平考试适应性试卷试题卷(六)数学

江西省2024年初中学业水平考试适应性试卷试题卷(六)数学试卷答案,我们目前收集并整理关于江西省2024年初中学业水平考试适应性试卷试题卷(六)数学得系列试题及其答案,更多试题答案请关注我们

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江西省2024年初中学业水平考试适应性试卷试题卷(六)数学试卷答案

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试题答案1~5CAABC6~10ACBBC11~15ACBCB16~20ABAAC21~23CAC24~27DBDC28~31BABD32~35CABD36~40FEADG41~45ACBBD46~50BDCAC51~55ACBDA56.moving57.a58.choice59.hours'60.finally61.tocome62.hasmade/hasbeenmaking63.stronger64.who/that65.by写作第一节参考范文:DearTom,Iamsorrytohearthatyouandyourbestfriendhavebeendriftingapartsinceyouenteredseniorhighschool.Buttakeiteasy.Tohelpyousaveyourfriendship,hereismyadvice.Firstly,Ifyoucan'tmakeittomeeteachotherfacetofacefrequentlylikebefore,itmightbeagoodideaforyoutokeepintouchbytextingregularly.Moreover,itisequallyimportanttomaketimeforyoutohaveamealtogetherorsimplydosomethingfunwithhim.IhopethesuggestionsabovewillworkforyouYours,LiHua第二节参考范文:TheoldladystoppedtoaskJanie,"Sweetie,areyouOK?"Janieshookherhead.Sheexpressedhersad-nessfornothavingenoughmoneytobuyhersickmomabirthdaycake.Hearingwhathadhappenedtothegirl'smother,theoldladycouldn'thelphuggingJanie,comfortedher,anddecidedtodosomethingforher.Shereachedintoherpocket,pulledoutsomemoney,andhandedittoJanie.Thensheledthegirlbacktothecakestore.Overhearingtheirconversation,Salfeltregretfulforhisbehaviorjustnow.WhenJaniewalkedbackin,Salgreetedherwithawarmsmilethistime."I'msorry,kid,"Salsaid."Youcanchooseanycakeforyourmotherforfree."Thoughsurprised,Janie'sfacelitupandshethankedSalalot.Janiewalkedcarefullytotheglasswindow,watchingtheredvelvetcakethatshehadbeenlookingforwardto.Withoutanydelay,SalpackedupthecakebeautifullyandhandedittoJanie,saying,"Bestwishestoyourmother,kid!"Janiesmiledandbe-lievedeverythingwouldbealright.【高一英语·参考答案第4页(共4页)】·23-148A·

分析若方程ex=ax+b(a>0,b∈R)有相等根,则等价为y=ax+b是f(x)=ex的切线,求函数的导数,利用导数的几何意义求出切线方程,建立a,b的关系,利用导数研究函数的最值和极值即可得到结论.

解答解:设函数f(x)=ex
若方程ex=ax+b(a>0,b∈R)有相等根,
则等价为y=ax+b是f(x)=ex的切线,
设切点为(x0,${e}^{{x}_{0}}$),
则f′(x)=ex
则切线斜率k=f′(x0)=${e}^{{x}_{0}}$,
则对应的切线方程为y-${e}^{{x}_{0}}$=${e}^{{x}_{0}}$(x-x0),
即y=${e}^{{x}_{0}}$x+${e}^{{x}_{0}}$(1-x0),
∵y=ax+b是f(x)=ex的切线,
∴a=${e}^{{x}_{0}}$,b=${e}^{{x}_{0}}$(1-x0),
即x0=lna,则b=a(1-lna),
则a+b=a+a(1-lna)=2a-alna,
设g(a)=2a-alna,
则g′(a)=2-(lna+1)=1-lna,
由g′(a)<0得a>e,此时函数单调递减,
由g′(a)>0得0<a<e,此时函数单调递增,
即当a=e时,函数g(a)=2a-alna取得极大值同时也是最大值g(e)=2e-elne=2e-e=e,
即a+b的最大值为e,
故答案为:e

点评本题主要考查函数最值的求解,根据条件转化为求函数的切线问题,利用导数研究函数的极值是解决本题的关键.综合性较强,难度较大.

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