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1、八年级数学第二学期数学讲义4一、填空题：（本大题共12题，每题2分， 满分24分）1若函数是一次函数，则的取值范围为 2已知一次函数的图像经过点，并与直线平行，那么这个一次函数解析式是 _3如果一次函数中y随x的增大而减小，那么这个一次函数一定不经过第_ 象限4在图中，将直线OA向上平移3个单位，所得直线的函数解析式为 第4题图5方程的解是 _ _第10题图6方程组的解为 7十二边形的内角和为_度8用换元法解方程.如果设，则原方程可化为y的整式方程是 9已知一个多边形的每个外角都为，那么这个多边形是 边形10如图，ABCD的周长是28cm，AC和BD交于O，OAB的周长比OBC的周长小2cm，
2、则AB = ，BC = .11解方程组时，可先化为 和 两个方程组12如果直线与两坐标轴所围成的三角形面积是9，则k的值为 二、选择题（本大题共6题，每题2分， 满分12分）13已知函数，若当时，；当时，a和b的大小关系是 （ ）（A）ab； （B）a=b； （C）ab； （D）不能确定14下列方程中，是二项方程的为（ ）（A）； （B）； （C）； （D）15下列方程中, 有实数解的是（ ）（A）； （B）； （C）； （D） 16 某灾区恢复生产，计划在一定时间内种60亩蔬菜，实际播种时每天比原计划多种3亩，因此提前一天完成任务，问实际种了几天？现设实际种了x天，则可列方程（ ）（A）；
3、（B）； （C）； （D）17已知平行四边形的一条边长为14，下列各组数中，能分别作它的两条对角线长的是（ ）（A）10与16； （B）12与16； （C）20与22； （D）10与1818一个面积为2的平行四边形被直线分成面积为x，y的两部分，则y与x之间的函数关系只可能是（ ）三、简答题（本大题共5题，每题6分， 满分30分）19解关于x的方程： 20解方程： 解： 解：21解方程组： 22解方程组： 解： 解：四、解答题（本大题共3题，每题8分， 满分24分）23如图，已知A（4，a），B（-2，-4）是一次函数ykxb的图象和反比例函数y的图象的交点（1）求反比例函数和一次函数的解祈式
4、；（2）求A0B的面积解： 24某区需修建一条2400米长的封闭式污水处理管道为了尽量减少施工对市民生活等的影响，实际施工比原计划每天多修10米，结果提前20天完成了任务试问实际每天修多少米？解： xOyAEFB（第25题图）25.（本题满分8分，第（4）小题为附加题，具体评分标准见参考答案）已知一次函数的图像与坐标轴交于、点（如图），平分，交轴于点. （1）求点的坐标；（2）求直线的表达式；(3) 过点作，垂足为，联结OF，试判断OFB的形状，并求OFB的面积.五、（本大题满分10分，第（1）小题2分，第（2）小题各4分）26如图已知一次函数y=x+7与正比例函数y=的图象交于点A，且与x轴
5、交于点B（1）求点A和点B的坐标；（2）过点A作ACy轴于点C，过点B作直线ly轴动点P从点O出发，以每秒1个单位长的速度，沿OCA的路线向点A运动；同时直线l从点B出发，以相同速度向左平移，在平移过程中，直线l交x轴于点R，交线段BA或线段AO于点Q当点P到达点A时，点P和直线l都停止运动在运动过程中，设动点P运动的时间为t秒当t为何值时，以A、P、R为顶点的三角形的面积为8？是否存在以A、P、Q为顶点的三角形是QA=QP的等腰三角形？若存在，求t的值；若不存在，请说明理由解：19已知一次函数的图像平行于直线，且经过点（2，-3）.（1）求这个一次函数的解析式；（2）当=6时，求的值.20已
6、知一次函数图像经过点A（-2，-2）、B（0，-4）.(1) 求、的值；（2）求这个一次函数与两坐标轴所围成的面积.21若直线分别交轴、轴于A、C两点，点P是该直线上在第一象限内的一点，PB轴，B为垂足，且SABC= 6.（1）求点B和P的坐标 .（2）过点B画出直线BQAP，交轴于点Q，并直接写出点Q的坐标.22某人因需要经常去复印资料，甲复印社按A4纸每10页2元计费，乙复印社则按A4纸每10页1元计费，但需按月付一定数额的承包费. 两复印社每月收费情况如图所示，根据图中提供的信息解答下列问题：（1）乙复印社要求客户每月支付的承包费是 元.待添加的隐藏文字内容3（2）当每月复印 页时，两复
7、印社实际收费相同.（3）如果每月复印页在250页左右时，应选择哪一个复印社?请简单说明理由.23小杰与小丽分别从相距27千米的A、B两地同时出发相向而行，3小时后相遇.相遇后两人按原来的速度继续前进， 小杰到达B地比小丽到达A地早 1小时21分.求两人的行进速度分别是多少？24.某街道因路面经常严重积水,需改建排水系统,市政公司准备安排甲乙两工程队承接这项工程.据评估,如果甲乙两队合作施工,12天可完成;如果甲队先做10天,剩下的由乙队单独承担,还需15天才能完成.问:甲乙两队单独完成此项工程各需多少天?Winger Tuivasa-Sheck, who scored two tries in
8、 the Kiwis 20-18 semi-final win over England, has been passed fit after a lower-leg injury, while Slater has been named at full-back but is still recovering from a knee injury aggravated against USA.Both sides boast 100% records heading into the encounter but Australia have not conceded a try since
9、Josh Charnleys effort in their first pool match against England on the opening day.Aussie winger Jarryd Hayne is the competitions top try scorer with nine, closely followed by Tuivasa-Sheck with eight.But it is recently named Rugby League International Federation player of the year Sonny Bill Willia
10、ms who has attracted the most interest in the tournament so far.The Kiwi - with a tournament high 17 offloads - has the chance of becoming the first player to win the World Cup in both rugby league and rugby union after triumphing with the All Blacks in 2011.Id give every award back in a heartbeat j
11、ust to get across the line this weekend, said Williams.The (lack of) air up there Watch mCayman Islands-based Webb, the head of Fifas anti-racism taskforce, is in London for the Football Associations 150th anniversary celebrations and will attend Citys Premier League match at Chelsea on Sunday.I am
12、going to be at the match tomorrow and I have asked to meet Yaya Toure, he told BBC Sport.For me its about how he felt and I would like to speak to him first to find out what his experience was.Uefa hasopened disciplinary proceedings against CSKAfor the racist behaviour of their fans duringCitys 2-1
13、win.Michel Platini, president of European footballs governing body, has also ordered an immediate investigation into the referees actions.CSKA said they were surprised and disappointed by Toures complaint. In a statement the Russian side added: We found no racist insults from fans of CSKA. Baumgartn
14、er the disappointing news: Mission aborted.The supersonic descent could happen as early as Sunda.The weather plays an important role in this mission. Starting at the ground, conditions have to be very calm - winds less than 2 mph, with no precipitation or humidity and limited cloud cover. The balloo
15、n, with capsule attached, will move through the lower level of the atmosphere (the troposphere) where our day-to-day weather lives. It will climb higher than the tip of Mount Everest (5.5 miles/8.85 kilometers), drifting even higher than the cruising altitude of commercial airliners (5.6 miles/9.17
16、kilometers) and into the stratosphere. As he crosses the boundary layer (called the tropopause),e can expect a lot of turbulence.The balloon will slowly drift to the edge of space at 120,000 feet ( Then, I would assume, he will slowly step out onto something resembling an Olympic diving platform.The
17、y blew it in 2008 when they got caught cold in the final and they will not make the same mistake against the Kiwis in Manchester.Five years ago they cruised through to the final and so far history has repeated itself here - the last try they conceded was scored by Englands Josh Charnley in the openi
18、ng game of the tournament.That could be classed as a weakness, a team under-cooked - but I have been impressed by the Kangaroos focus in their games since then.They have been concentrating on the sort of stuff that wins you tough, even contests - strong defence, especially on their own goal-line, co
19、mpleting sets and a good kick-chase. Theyve been great at all the unglamorous stuff that often goes unnoticed in the stands but not by your team-mates.It is as though their entire tournament has been preparation for the final.In Johnathan Thurston, Cooper Cronk, Cameron Smith and either Billy Slater
20、 or Greg Inglis at full-back they have a spine that is unmatched in rugby league. They have played in so many high-pressure games - a priceless asset going into Saturday.The Kiwis are a lot less experienced but winning a dramatic match like their semi-final against England will do wonders for their confidence.They defeated Australia in the Four Nations final in 2010 and the last World Cup, and know they can rise to the big occasion.
