填空题[A]Hemphasbeencultivatedbymanyculturesforthousandsofyears.Itproducesfibrewhichcanbemadeintopaper,fuel,oils,textiles,food,andrope.Formanycenturies,itwasessentialtotheeconomiesofmanycountriesbecauseitwasusedtomaketheropesandcablesusedonsailingships;colonialexpansionandtheestablishmentofaworld-widetradingnetworkwouldnothavebeenpossiblewithouthemp.Nowadays,ships'cablesareusuallymadefrom'wireorsyntheticfibres,butscientistsarenowsuggestingthatthecultivationofhempshouldberevivedfortheproductionofpaperandpulp.Accordingtoitsproponents,fourtimesasmuchpapercanbeproducedfromlandusinghempratherthantress,andmanyenvironmentalistsbelievethatthelarge-scalecultivationofhempcouldreducethepressureonCanada'sforests.[B]MuchofCanada'sforestryproductiongoestowardsmakingpulpandpaper.AccordingtotheCanadianPulpandPaperAssociation,Canadasupplies34%oftheworld'swoodpulpand49%ofitsnewsprintpaper.Ifthesepaperproductscouldbeproducedinsomeotherway,Canadianforestscouldbepreserved.Recently,apossiblealternativewayofproducingpaperhasbeensuggestedbyagriculturalistsandenvironmentalists:aplantcalledhemp.[C]Inrecentyears,twomajormovementsforlegalizationhavebeengatheringstrength.OnegroupofactivistsbelievesthatALLcannabisshouldbelegal--boththehempplantandthemarijuanaplant--andthattheuseofthedragmarijuanashouldnotbeanoffense.Theyarguethatmarijuanaisnotdangerousoraddictive,andthatitisusedbylargenumbersofpeoplewhoarenotcriminalsbutproductivemembersofsociety.Theyalsopointoutthatmarijuanaislesstoxicthanalcoholortobacco.[D]However,thereisaproblem:hempisillegalinmanycountriesoftheworld.Thisplant,sousefulforfibre,rope,oil,fuelandtextiles,isaspeciesofcannabis,relatedtotheplantfromwhichmarijuanaisproduced.[E]Theotherlegalizationmovementisconcernedonlywiththehempplantusedtoproducefibre;thisgroupwantstomakeitlegaltocultivatetheplantandsellthefibreforpaperandpulpproduction.Thissecondgrouphashadamajortriumphrecently:in1997,Canadalegalizedthefarmingofhempforfibre.Forthefirsttimesince1938,hundredsoffarmersareplantingthiscrop,andsoonwecanexpecttoseepulpandpaperproducedfromthisnewsource.[F]Inthelate1930s,amovementtobanthedrugmarijuanabegantogatherforce,resultingintheeventualbanningofthecultivationnotonlyoftheplantusedtoproducethedrug,butalsoofthecommercialfibre-producinghempplant.AlthoughbothGeorgeWashingtonandThomasJeffersongrewhempinlargequantitiesontheirownland,anyAmericangrowingtheplanttodaywouldsoonfindhimselfinprison--despitethefactthatmarijuanacannotbeproducedfromthehempplant,sinceitcontainsalmostnoTHC(theactiveingredientinthedrug).[G]Everysecond,1hectareoftheworld'srainforestisdestroyed.That'sequivalenttotwofootballfields.AnareathesizeofNewYorkCityislosteveryday.Inayear,thataddsupto31millionhectares--morethanthelandareaofPoland.Thisalarmingrateofdestructionhasseriousconsequencesfortheenvironment;scientistsestimate,forexample,that137speciesofplant,insectoranimalbecomeextincteverydayduetologging.InBritishColumbia,where,since1990,thirteenrainforestvalleyshavebeenclear-cut,142speciesofsalmonhavealreadybecomeextinct,andthehabitatsofgrizzlybears,wolvesandmanyothercreaturesarethreatened.Logging,however,providesjobs,profits,taxesforthegovernmentandcheapproductsofallkindsforconsumers,sothegovernmentisreluctanttorestrictorcontrolit.

填空题若二次型的正、负惯性指数都是1，则a=______．

填空题若∫f(x)dx=arctan x+C，则f(x)=______。

填空题设z=sin(xy)，则dz=______。

填空题设λ 1 ，λ 2 ，λ 3 是三阶矩阵A的三个不同特征值，α 1 ，α 2 ，α 3 分别是属于特征值λ 1 ，λ 2 ，λ 3 的特征向量，若α 1 ，A(α 1 +α 2 )，A 2 (α 1 +α 2 +α 3 )线性无关，则λ 1 ，λ 2 ，λ 3 满足______

填空题∫sec 2 5xdx=______．

填空题已知则r(A-E)+r(2E+A)=________．

填空题斜边长为l的直角三角形中，最大周长为______．

填空题若实对称矩阵A与矩阵合同，则二次型xTAx的规范形为________．

填空题设有摆线x=a(t-sint)，y=a(1-cost)(0≤t≤2π)的第一拱L，则L绕x轴旋转一周所得旋转面的面积S=______．

填空题设三阶行列式D 3 的第二行元素分别为1、-2、3，对应的代数余子式分别为-3、2、1，则D 3 =_________。

填空题设f(x)=2 x ，g(x)=x 2 +1，则f[g"(x)]=______．

填空题从社会效益和经济效益出发，我市投入资金进行生态环境建设，并以此发展旅游产业，根据规划，2003年投入800万元，以后每年投人都比上一年减少20%；2003年我市旅游业收入估计为400万元，由于该项建设对旅游业的促进作用，预计今后每年旅游业的收入都比上一年增加25%．那么可以确定a＜b且m＞n. (1)设2005年投人为a万元，收入为b万元；2003年至2005年总投人为m万元，总收入为n万元； (2)设2004年投入为a万元，收人为b万元；2003年至2004年总投入为m万元，总收入为n万元．

填空题函数的间断点为x=________．

填空题函数y=x3-2x+1在区间[1，2]上的最小值为______．

填空题设函数微分为，则_____.

填空题设X1，X2，…，X100相互独立且在区间[-1，1]上同服从均匀分布，则由中心极限定理

填空题 设平面π的方程为x-y+2z=1，则过点A(2，-1，2)且与平面π垂直的直线方程为______．

填空题微分方程y/=3x2的通解为y=

填空题设二次型2x 1 2 +x 2 2 +x 3 2 +2x 1 x 2 +ax 2 x 3 的秩为2，则a=__________．