直通车-高数-零基础阶段测试卷-解析时间:120分钟满分:100分1.设(,)fxy为连续函数,则1400d(cos,sin)dfrrrr等于()(A)22120d(,)dxxxfxyy−.(B)221200d(,)dxxfxyy−.(C)22120d(,)dyyyfxyx−.(D)221200d(,)dyyfxyx−.【答案】(C)【解析】由题设可知积分区域D如右图所示,显然是Y型域,则原式22120d(,)dyyyfxyx−=.故选(C).2.求极限(1)3232342lim753xxxxx→++=+−.(2)32320342lim753xxxxxxx→++=+−.【答案】(1)37,(2)23−【解析】(1)3233234233423lim=lim5375377xxxxxxxxxx→→++++=+−+−.(2)322322003423422limlim7537533xxxxxxxxxxxx→→++++==−+−+−.3.1arctanarctan0)xxx+=(.【答案】2【解析】222111(arctanarctan)0111xxxxx−+=+=++故,1arctanarctanxCx+=,其中C为某一常数。当1x=时,1arctanarctan4xx==,故1arctanarctanxx+=2.4.π3222π2(sin)cosdxxxx−+=_______.【答案】8【解析】由题干可知,积分区间是对称区间,利用被积函数的奇偶性可以简化计算.在区间[,]22−上,32cosxx是奇函数,22sincosxx是偶函数,故()()322322222222221sincoscossincossin24xxxdxxxxxdxxdx−−−+=+=221(1cos4)8xdx−=−.8=5.设数列nx满足110,sin(1,2,)nnxxxn+==(Ⅰ)证明limnnx→存在,并求该极限;(Ⅱ)计算211limnxnnnxx+→.【解析】(Ⅰ)因为10x,则210sin1xx=.可推得10sin1,1,2,nnxxn+==,则数列nx有界.于是1sin1nnnnxxxx+=,(因当0sinxxx时,),则有1nnxx+,可见数列nx单调减少,故由单调减少有下界数列必有极限知极限limnnx→存在.设limnnxl→=,在1sinnnxx+=两边令n→,得sinll=,解得0l=,即lim0nnx→=.(Ⅱ)因22111sinlimlimnnxxnnnnnnxxxx+→→=,由(Ⅰ)知该极限为1型,令ntx=,则,0nt→→,而222sin111111sin1000sinsinsinlimlim11lim11tttttttttttttttt−−→→→=+−=+−,又23300001sinsincos1sin1lim1limlimlim366tttttttttttttt→→→→−−−−====−.(利用了sinx的麦克劳林展开式)故2211116sinlimlimennxxnnnnnnxxxx−+→→==.6.设函数322,0,arcsin()6,0,0,1,sin2axaxxxxfxxxexaxx−...