(完整版)苏教版八年级数学(下)第八章分式复习讲义

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College students village officer two learning experiences and 11 seriously practice education to become the primary qualified village \e would be no new China without the Communist Party......\still reverberate in the ears of the revolution. When I was little I was young pioneers when every time I hear a similar sound, I'm excited, deeply impressed by those Communist revolutionary martyr spirit. In the process of growing up, experienced war ancestor master is also often told me about his story as a soldier shed their blood, let me feel the maternal grandparents the noble character of Alex as a senior party member. Little blood was determined to grow in my heart I want to be like his grandparents Alex, soldiers on TV-like, grows up to become a soldier, party members engaged in the great cause of the motherland in the future. College, after tireless efforts I glory to become a Communist Party Member, became a member of 87 million members. However, under the washing of the passage of time and in real life, although he was a Communist Party Member, but too far up from the older party members, they have spirit, thinking, consciousness and character, and now me, or we are a young party that seems to be missing something. Now as a basic means of college students village officer, Assistant to the Secretary of the General party branch and grass-roots party members, is my party recently, when the \haps on my own, or are a lot like me, thinking there are some slack, at some indifferent on the ideal and faith of young party members, is a very good chance. Because of this study, is no longer the cadres to learn a few key, but something we all 87 million Communist Party members to join, and the learning is not a short-term focus on learning, but long-term regular learning. ake this opportunity to speak I will carefully study the party Constitution and party rules, series, striving to be the qualified partymembers, competent college students village officer. School-the cornerstone. Ideological building is the key to do well in everything. No ideals and beliefs, ideals and beliefs is not determined, mentally %um\ be more regulation out of bounds, paomaodilou problems. 18 of the party since the Party Central Committee continued to promote the party's ideological and political construction, whether the educational practice of the mass line of the party, or the \e-three\education practices, are from the mental effort. As a grass-roots party members, ideologically determined is particularly important, so after work I will conscientiously abide by the party Constitution, strengthen party spirit, belief and faith, be sure to always maintain a high degree of consensus with the Party on the thoughts and actions. Party, party, party party, party party, subjected to armed socialist theory system with Chinese characteristics, guiding practice to supplement calcium, and strengthen the spirit of self-discipline of the base, pave the way for politically. Par enhancing awareness, learn to stand on the issues, on the overall situation of the第八章分式复习讲义

【知识点 1】分式

1、分式的定义：一般地，如果A、B表示两个________，并且______中含

有字母，那么代数式__________叫做分式。

2、分式有意义的条件：___________。分式为0的条件：___________

【基础练习】 1、下列各式：

3a?b11x中，分式有_______________ ,,x2?y2,5,,a72x?18?2、一件工作，甲单独做a小时完成，乙单独做b小时完成，则甲、乙合作小时完成

x2?1

3、若分式的值为0，则x的取值为_________________

x?1

x?1x有意义，当x 时，分式无意义。 x?32x?3【知识点 2】分式的基本性质

1、分式的基本性质：分式的_____________都乘以（或除以）_____________,

分式的值____________ AAgMAA?（）用式子表示就是：=,=(其中，M是___________________)

BB（g ）BB?（）2、分式的约分：根据_____________，把分式的_____________分别______它

们的___________，叫做分式的约分。通常把分式约成________

3、分式的通分：同分母的分式通分：___________________________________. 异分母的分式通分：___________________________________. 对分式进行通分的关键是：___________________________. 最简公分母：________________________________,

分母如果是多项式，应该先__________________,再__________________.

4、当x 时，分式【基础练习】 1、如果把分式

2xy中的x和y都扩大3倍，那么分式的值（） x?y A、扩大3倍 B、缩小3倍 C、缩小6倍 D、不变

2y2y2?aa22-m1???2、填空，， 1?y（）1?a（）4?m2（）3、约分

x2?y2x2?9x?xy1+2x 2， 2， 2， 223x?6xy?3y9?6x?xy?14x?4x?1College students village officer two learning experiences and 11 seriously practice education to become the primary qualified village \e would be no new China without the Communist Party......\still reverberate in the ears of the revolution. When I was little I was young pioneers when every time I hear a similar sound, I'm excited, deeply impressed by those Communist revolutionary martyr spirit. In the process of growing up, experienced war ancestor master is also often told me about his story as a soldier shed their blood, let me feel the maternal grandparents the noble character of Alex as a senior party member. Little blood was determined to grow in my heart I want to be like his grandparents Alex, soldiers on TV-like, grows up to become a soldier, party members engaged in the great cause of the motherland in the future. College, after tireless efforts I glory to become a Communist Party Member, became a member of 87 million members. However, under the washing of the passage of time and in real life, although he was a Communist Party Member, but too far up from the older party members, they have spirit, thinking, consciousness and character, and now me, or we are a young party that seems to be missing something. Now as a basic means of college students village officer, Assistant to the Secretary of the General party branch and grass-roots party members, is my party recently, when the \haps on my own, or are a lot like me, thinking there are some slack, at some indifferent on the ideal and faith of young party members, is a very good chance. Because of this study, is no longer the cadres to learn a few key, but something we all 87 million Communist Party members to join, and the learning is not a short-term focus on learning, but long-term regular learning. ake this opportunity to speak I will carefully study the party Constitution and party rules, series, striving to be the qualified partymembers, competent college students village officer. School-the cornerstone. Ideological building is the key to do well in everything. No ideals and beliefs, ideals and beliefs is not determined, mentally %um\ be more regulation out of bounds, paomaodilou problems. 18 of the party since the Party Central Committee continued to promote the party's ideological and political construction, whether the educational practice of the mass line of the party, or the \e-three\education practices, are from the mental effort. As a grass-roots party members, ideologically determined is particularly important, so after work I will conscientiously abide by the party Constitution, strengthen party spirit, belief and faith, be sure to always maintain a high degree of consensus with the Party on the thoughts and actions. Party, party, party party, party party, subjected to armed socialist theory system with Chinese characteristics, guiding practice to supplement calcium, and strengthen the spirit of self-discipline of the base, pave the way for politically. Par enhancing awareness, learn to stand on the issues, on the overall situation of the4、

1y1,?2,的最简公分母是。 2(x?1)y4x6xyz5、通分（1）

32a2 （2）2 ，，x?26-3xa?42?a【知识点 3】分式的加减

1、同分母的分式相加减：分母_____________，分子______________ 2、异分母的分式相加减: 先_______________，后________________

【基础练习】

111222b2?计算：（1）（2）2 （3）a?b? ?a?bm?9m?3y?x2y?2x

【知识点 4】分式的乘除 1、分式乘分式，__________________做积的分子，_____________做积的分母。 2、分式除以分式，先__________________________，再____________________。 3、分式的混合运算顺序,_____________________________________________。

【基础练习】

?x2?41x2?2x?1x?2?x（-1）?计算：（1）（2） ???2?2x?2x?4?x?4x?4x?2?x?2

【知识点 5】分式方程

1、分式方程：___________中含有未知数的__________叫做分式方程。 2、解分式方程的步骤：____________________________________

在方程的两边同时乘_______________,可以将分式方程转化为一元一次方程求解。解分式方程一定要___________________. 3、分式方程产生增根的原因：__________________________

4、列分式方程的步骤：______________________________________。

10x?46x5x?11? ??1 （2）2? （3）222x?55?2xx?3xx?x?1?x?1 2、 3、设A?

4、A、B两地相距48千米，一艘轮船从A地顺流航行至B地，又立即从B地逆流返回A地，共用去9小时，已知水流速度为4千米/时，若设该轮船在静水中的速度为x千米/时，则可列方程（） A、若方程

xk会产生增根，试求k的值。 ?2?x?3x?3x3，B?2?1，当x为何值时，A与B的值相等？ x?1x?148484848489696??9 B、??9 C、?4?9 D、??9 x?4x?44?x4?xxx?4x?45、A、B两地的距离是80公里，一辆公共汽车从A地驶出3小时后，一辆小汽车也从A地出发，它的速度是公共汽车的3倍，已知小汽车比公共汽车迟20分钟到达B地，求两车的速度。

6、为加快西部大开发，某自治区决定新修一条公路，甲、乙两工程队承包此项工程。如果甲工程队单独施工，则刚好如期完成；如果乙工程队单独施工就要超过6个月才能完成，现在甲、乙两队先共同施工4个月，剩下的由乙队单独施工，则刚好如期完成。问原来规定修好这条公路需多长时间？

1m3x12x2?4,(a?b),,1、下列各式中，,,?，分式有。

3x22?y3?x?22、当x 时，分式

x?1x有意义；当x 时，分式无意义； x?32x?3x2?4

当x 时，分式的值为零。

x+2

a?b(　　　)a2?aa?1x2?xy(　　　)???3、填空：（1）；（2）；（3）； 22(　　　)cxabxabm2?m?（4）

mn4、把分式

?n? ；（5）x?y??2?2x?2y(x?y)；

x?y中的字母x和y同时变为原来的3倍，分式的值； 22x?y5、请你写一个关于x的分式，使此分式当x?3时，它的值为2。

116、分式、的最简公分母是。

x?1x?27、计算：（1）