题目

已知反比例函数 和一次函数y=-x+a-1（a为常数）（1）当a＝5时，求反比例函数与一次函数的交点坐标（5分） （2）是否存在实数a，使反比例函数与一次函数有且只有一个交点，如果存在，求出实数a，如果不存在，说明理由（5分） 答案：试题分析：（1）当a=5时，一次函数为y=-x+4 则交点满足： 解得  ， ∴交点坐标为 或 （2）把y=-x+a-1代入反比例函数可得：x（-x+a-1）=1 即-x 2 +（a-1）x-1=0 当反比例函数与一次函数有且只有一个交点时，△=（a-1） 2 -4=0 解得a=3或a=-1 也即存在实数a，当a=3或a=-1时，有且只有一个交点 考点：反比例函数Dining Room Table with China Cabinet For Sale：Dining room table with six chairs and china cabinet(瓷器厨)．$400.00 or Best Offer．Saginaw Township·989-295-7158．Web Id:MLV6567730 Huge Yard Sale Huge Yard Sale!! Tuesday May l7th 8-4；Wednesday May 18th:8-5;708 Woodside Lane. Selling：Baby Girl Clothes 0-12 months$ 0.25一$1；Boy Clothes 240—12 months $ 0.25；Toys $ 0.10一$10；Boys’ shoes size 6-11，Girls’ shoes size 0-4,all $ 0.25；Christmas Tree $5．Books! Educational and Fun from baby to pre-teen，all $ 0.10．Women’s clothing，coats and lots more! There’s something here for everyone! Come check us out! Everything must go!Web Id:MLV6S67328 Yorkie Puppy(幼犬)for a good home This joy is being raised in my home and thus is learning all the ood habits and has always been the best think in my life．She is too sweet to be called a dog．She’s just l3 weeks old but strong enough to be called a big girl．If interested in getting the joy，then  please email to gmoorel902@blumail.orgWeb Id:MLV6566545 Sporting Goods For Sale Elive Auction(拍卖)is hosting a huge online auction Tuesday May l7,201 on our website，www.eliveauctlons.com. We have things such as practice baseball and softballs, rubber home plates，etc .along with other things. Don’t miss out on this amazing opportunity to get unbelievable deals!! Bid(竞拍) online at www．Eliveauctions.com! Only online bidding ccepted.Web Id: MT v6562988小题1:To buy some table or chairs, you may want information about         .A．Web ld: MLV6562988B．Web Id: MLV6567328C．Web Id: MLV6567730D．Web Id: MLV6559374小题2:How much will a pair of boy shoes size 10 cost you in the Huge Yard Sale?A．$ 1.B．$0.25.C．$ 10.D．$ 12.小题3:Which of the following ways can help you learn more about a dog?A．Visiting www. Lulu.com.B．Visiting www. eliveauctions.com.C．Calling 989-295-7158.D．Email to gmoorel902@ blumail.org.小题4:What do we know from Elive Auctions?A．The prices can not be changed.B．Generally goods there are expensive.C．There're also books about sports.D．Goods are mainly about sporting ones.