题目

如图，在平面直角坐标系xOy中，已知点A（0，8），B（6，0），点C（3，a）在线段AB上． （1） 则a的值为； （2） 若点D（－4，－3），求直线CD的解析式； （3） 点（－5，－4）在直线CD上吗？说明理由． 答案：【1】4 解：设直线CD函数解析式为y＝kx+b 把C（3，4），D（－4，－3）代入y＝kx+b中 则 {3k+b=4−4k+b=−3解得 {k=1b=1∴直线CD函数解析式为y=x+1 解：当x=－5时 y=－5+1=－4 所以点（－5，－4）在直线CD上Basic Study Manual (Hardcover): $37.50Future success depends on the ability to learn. Here are the answers to the questions most often asked by students. Read this book and learn:*What the three barriers to study are and what to do about them * What to do if you get tired of a subject you are studying*Twenty-six simple drills to help you learn how to study easily, rapidly and with full understandingBuy and read the Basic Study Manual and use it to dramatically improve your ability to study.Study Skills for Life (Hardcover): $31.99L. Ron Hubbard’s study technology for teenagers opens the door to their future success by giving them advice on how to study and learn. Fully illustrated（插图）for easy comprehension.Learning How to Learn (Hardcover):$24.99The basics of effective study for 8 to 12-year-olds, fully illustrated. Children who read and apply the materials in this book can regain their liking for study. Get this book for a child you want to see win at his studies!How to Use a Dictionary Picture Book for Children (Hardcover):$34.90In spite of billions of dollars spent on “educational research”, children are not taught the most basic skills of learning: how to use a dictionary. Written for children 8 to 12-year-old, this fully illustrated book will teach your children:*How to find words in a dictionary*The different ways that words are used *How to use a dictionary to correctly pronounce wordsAt last, you’ll just pay 50% for these books before May 1, 2007. （260 words）1.The four books can mostly satisfy       .A.teachersB.childrenC.adultsD.parents2.If you want to improve your ability to study, you’ll probably choose     .A.Basic Study ManualB.Study Skills for LifeC.Learning How to LearnD.How to Use a Dictionary Picture Book for Children3.If you buy all the fully illustrated books before May 1, 2007, you will pay about      .A.$56B.$111C.$46D.$924.This passage aims to      .A.introduce new books to readersB.guide readers to choose booksC.encourage people to buy the booksD.enlarge students’ knowledge about books