归纳解一元一次不等式组的一般步骤课件.pptx

,10.5 一元一次不等式组,邢台市第二十五中学 李青,第一课时 解一元一次不等式组,【设计说明】,感谢您购买本产品，本页将对该模版的设计进行补充说明：,模版标题字体：方正静蕾简体、新蒂黑板报正文字体：华文细黑，字体下载后直接安装即可,一、复习引入 1、什么叫做一元一次不等式？一个未知数，未知数的次数是1，不等号两边都是整式 2、解一元一次不等式的步骤有哪些？,（1）去分母；,（2）去括号；,（3）移项；,（4）合并同类项；,(5)系数化为1,解一元一次不等式并将解集表示在数轴上上,一、回顾旧知：,二、新课引入,据悉，鹿晗的演唱会将于10月份在北京举行，由于座位位置不同演唱会的门票也不相同。,门票最高价格不高于2000；最低价格不低于300；,能用不等式表示吗？,x2000，x300,不等式组：,由若干个不等式组成的一组不等式,一元一次不等式组,1.能够说出一元一次不等式组的定义并进行识别.,2.能在数轴上正确表示一元一次不等式组的解集（重点）,3.熟练求解一元一次不等式组.(重、难点）,学习目标：,一元一次不等式组：,含有同一个未知数的一元一次不等式的不等式组，叫做一元一次不等式组。,(1)不等式必须是只含有同一个未知数；(2)每个不等式必须为一元一次不等式；(3)不等式的数量至少是两个。,注意：,练一练,判断下列各不等式组是否为一元一次不等式组，并说明理由.,否,否,是,是,是,是,如何求不等式组的解集呢？,此不等式组的解集为300 x2000,公共部分,什么是不等式组的解集呢？,一元一次不等式组中所有不等式解集的公共部分,求下列不等式组的解集:,不等式组的解集为 x 2；,不等式组的解集为 x 0；,写解集规律,同大取大,不等式组的解集为 xb；,(ab),求下列不等式组的解集:,不等式组的解集为 x 1；,写解集规律,不等式组的解集为 x-1。,同小取小,不等式组的解集为 xa；,(ab),求下列不等式组的解集:,不等式组的解集为 1 x 2；,写解集规律,不等式组的解集为-1x 0；,大小小大中间找,(ab),不等式组的解集为 axb；,求下列不等式组的解集:,不等式组无解；,写解集规律,不等式组无解；,大大小小无解了,(ab),不等式组无解,a,a,a,b,xa,x b,。,。,a,。,。,b,。,。,b,。,。,b,一元一次不等式组的解集的规律图析,(若当 ab时),同大取大,同小取小,大小小大中间找,大大小小无解了,求不等式组解集的口诀：,同大取大同小取小大小小大中间找大大小小无解了,举手抢答：,快速确定下列不等式组的解集：,解集为 x3.5,解集为x1,无解,解不等式，得 x9解不等式，得 x1,不等式组的解集为x1,例题解析,如何解不等式组呢？,解：,1、解每个一元一次不等式,2、根据口诀写出一元一次不等式组的解集,解一元一次不等式组的一般步骤：,2x-1x+1x+84x-1,解下列不等式组,试一试，相信你能行,(1),吴,蜀,KEY WORDS,KEY WORDS,.,魏,比一比：,（3）已知4a+5和2a-4的值都是负数，求a的取值范围。,吴,魏,KEY WORDS,KEY WORDS,.,蜀,吴,蜀,KEY WORDS,KEY WORDS,.,魏,吴,蜀,KEY WORDS,KEY WORDS,吴,魏,吴,KEY WORDS,KEY WORDS,蜀,魏,还有得出不等式组解集的其他方法吗？,利用口诀来试试吧,2、已知4a+5和2a-4的值都是负数，求a的取值范围。,1.能够说出一元一次不等式组的定义并进行识别.,2.能在数轴上正确表示一元一次不等式组的解集（重点）,3.熟练求解一元一次不等式组.(重、难点）,学习目标：,四、,达标测评,1、下列各式中，是一元一次不等式组有哪几个？,1、（1）的解集为。,（2）的解集为。,2、不等式组 的解集为。,3、求不等式组的解集,4、试求 的整数解。,5、代数式1-2k的值不大于5，但大于-1，求k的取值范围。,结束,提高题：,解不等式组,思考：,如果 的解集是x2，那么m的取值范围是（）,A m2 B m2C m2 D m2,由特殊到一般,类比思想,KEY WORDS,KEY WORDS,.,数形结合,谢谢大家！,四、例题解析,例1.解下列不等式组：,解:解不等式，得,在同一个数轴上表示不等式，的解集为,解不等式，得,所以原不等式组的解集为,0 2 4,例1:解下列不等式组,解:解不等式,得，解不等式,得，把不等式和 的解集在数轴上表示出来:,所以不等式组的解集:,解:解不等式,得，解不等式,得，把不等式和 的解集在数轴上表示出来:,这两个不等式的解集没有公共部分，所以不等式组无解。,A designer can use default text to simulate what text would look like.A designer can use default text to simulate what text would look like.A designer can use default text to simulate what text would look like.A designer can use default text to simulate what text would look like.,这里可以是标题,标题,A designer can use default text to simulate what text would look like.,标题,A designer can use default text to simulate what text would look like.,标题,A designer can use default text to simulate what text would look like.,02,论文综述简介,S,W,O,T,A designer can use default text to simulate what text would look like.If it is not real text.,小标题,A designer can use default text to simulate what text would look like.If it is not real text.,小标题,A designer can use default text to simulate what text would look like.If it is not real text.,小标题,A designer can use default text to simulate what text would look like.If it is not real text.,小标题,A designer can use default text to 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