2018年七年级数学上册第二章整式的加减2-1整式2-1-3多项式及整式备课资料教案(新版)新人教版

The Union Jack was the name of the flag made when England,Scotland and Ireland joined together to make one country.

2018年七年级数学上册第二章整式的加减2-1整式2-1-3

多项式及整式备课资料教案（新版）新人教版

知识点1：多项式

几个单项式的和叫多项式,其中每一个单项式都叫多项式的项,不含字母的项叫常数项,各项中次数最高的项的次数就表示多项式的次数,多项式中单项式的个数就是多项式的项数.

关键提醒:(1)多项式必须由单项式组成,体现和的运算法则. (2)不要把多项式的次数与单项式的次数混淆,误认为多项式的次数是各项次数之和.

(3)多项式的项包括它前面的性质符号.

(4)通常将一个多项式写成按某个字母的次数由高到低或者由低到高的顺序排列. 知识点2：整式

单项式和多项式统称为整式.

归纳整理:整式 考点1：多项式的判定

【例1】在-m2,8xy,4a2-b3,3.14,,+q,中,单项式有个,多项式有 个.

答案:3;3

Sailors used to speak of a “jack” when they meant a flag which was set near the bow of a sailing ship.The flag showed the coun to which the ship belonged.The Union Jackbecame the flag of Great Britain.1 / 2

The Union Jack was the name of the flag made when England,Scotland and Ireland joined together to make one country.

点拨：是数与字母的商,不是单项式也不是多项式,+q是两个单项式的和,是多项式;可看作+,是多项式,易误认为是单项式而出错. 考点2：多项式的系数和次数

【例2】若-3axym是关于x,y的单项式,且系数为-6,次数为3,则a= ,m= .

答案:a=2,m=2.

点拨:“关于x,y的单项式”说明只有x,y才是单项式中的字母,a只是系数的一部分,所以-3a是系数,也就是-6,即-3a=-6,解得a=2.而单项式的次数是x,y的指数和(1+m),也就是3. 因此1+m=3得m=2.考点3：整数的判定

【例3】在-2,0,,x2+3x,b,中,整式有 . 答案:-2,0,,x2+3x,b.

点拨:判断一个式子是否为整式,关键是看它是不是单项式或多项式,由单项式的定义可知:-2,0,,b都是单项式;由多项式的定义可知:x2+3x是多项式;不是单项式,也不是多项式,因此它不是整式.

Sailors used to speak of a “jack” when they meant a flag which was set near the bow of a sailing ship.The flag showed the coun to which the ship belonged.The Union Jackbecame the flag of Great Britain.2 / 2