初中數(shù)學(xué)魯教版(五四制)六年級上冊第三章整式及其加減-提技能·題組訓(xùn)練33

1、提技能題組訓(xùn)練單項(xiàng)式的相關(guān)概念1.下列式子中單項(xiàng)式的個數(shù)是()3a,12xy2,-5xy4,a,-x,2B. 5C. 62.下面說法中,正確的是()+1是單項(xiàng)式B.1xyC.xy-12是單項(xiàng)式D.【互動探究】含分母的式子,在什么情況下是單項(xiàng)式?什么情況下不是單項(xiàng)式?3.下列語句中錯誤的是()A.數(shù)字0是單項(xiàng)式B.單項(xiàng)式-x的系數(shù)是-1,次數(shù)是1是二次單項(xiàng)式23的系數(shù)是-【變式訓(xùn)練】下列說法中正確的是(),a不是單項(xiàng)式abcx2y2的系數(shù)為0,次數(shù)為24.單項(xiàng)式-ab2c3的系數(shù)和A.系數(shù)為-1,次數(shù)為3B.系數(shù)為-1,次數(shù)為5C.系數(shù)為-1,次數(shù)為6D.以上說法都不對5.單項(xiàng)式-5x2y的系數(shù)

2、是.6.已知-2xmyn+1的次數(shù)為2,求3m+3n-5的值.【變式訓(xùn)練】如果(m+1)2x2yn+1是關(guān)于x,y的六次單項(xiàng)式,求m,n的值.多項(xiàng)式、整式的概念1.多項(xiàng)式-15x2y+22A.1515C.152.多項(xiàng)式5x2-2xy-3的常數(shù)項(xiàng)為()A.沒有B.33.式子x2+5,-1,-3x+2,5x,x2+1個個個個4.把下列各式填在相應(yīng)的大括號里:x-7,13x,4ab,23a,5-3x,y,st,x+13,x7+y7,x2+單項(xiàng)式集合;多項(xiàng)式集合;整式集合.5.下列各式:ab,-6,1x,m+n3,5x+3,-2x7,m2-2m+1,-p3q,【錯在哪？】作業(yè)錯例 課堂實(shí)拍確定單項(xiàng)式-

3、2(1)找錯:從第_步開始出現(xiàn)錯誤.(2)糾錯:_ QUOTE 單項(xiàng)式-2x2y提技能題組訓(xùn)練單項(xiàng)式的相關(guān)概念1.下列式子中單項(xiàng)式的個數(shù)是()3a,12xy2,-5xy4,a,-x,2B. 5C. 6【解析】選C.根據(jù)單項(xiàng)式的定義可知,3a,12xy2,-5xy4,a【知識歸納】單項(xiàng)式的判斷技巧判斷一個式子是否是單項(xiàng)式,關(guān)鍵是看式子中的數(shù)與字母、字母與字母之間是否只有乘法運(yùn)算或乘方運(yùn)算,如果含有加、減、除法運(yùn)算,那它就不是單項(xiàng)式.2.下面說法中,正確的是()+1是單項(xiàng)式B.1xyC.xy-12是單項(xiàng)式D.【解析】選D. xy+1含有加法運(yùn)算不是單項(xiàng)式;1xy分母中含有字母不是單項(xiàng)式;x【互動探

4、究】含分母的式子,在什么情況下是單項(xiàng)式?什么情況下不是單項(xiàng)式?【解析】分母是數(shù)字,分子是單項(xiàng)式時是單項(xiàng)式,分子不是單項(xiàng)式或分母中含有字母時不是單項(xiàng)式.3.下列語句中錯誤的是()A.數(shù)字0是單項(xiàng)式B.單項(xiàng)式-x的系數(shù)是-1,次數(shù)是1是二次單項(xiàng)式23的系數(shù)是-【解析】選是四次單項(xiàng)式.【變式訓(xùn)練】下列說法中正確的是(),a不是單項(xiàng)式abcx2y2的系數(shù)為0,次數(shù)為2【解析】選C.單獨(dú)一個數(shù)或字母也是單項(xiàng)式,所以-5,a是單項(xiàng)式;-abc2的系數(shù)是-124.單項(xiàng)式-ab2c3A.系數(shù)為-1,次數(shù)為3B.系數(shù)為-1,次數(shù)為5C.系數(shù)為-1,次數(shù)為6D.以上說法都不對【解析】選C.單項(xiàng)式-ab2c3【知識

5、歸納】單項(xiàng)式的系數(shù)(1)當(dāng)一個單項(xiàng)式的系數(shù)是1或-1時,“1”通常省略不寫.(2)單項(xiàng)式的系數(shù)包括它前面的性質(zhì)符號.(3)單項(xiàng)式的系數(shù)只與數(shù)字因數(shù)有關(guān),與字母無關(guān).(4)單項(xiàng)式的數(shù)字因數(shù)是帶分?jǐn)?shù)時,通常寫成假分?jǐn)?shù)的形式.5.單項(xiàng)式-5x2y的系數(shù)是.【解析】因?yàn)?5x2y=-5x2y,所以該單項(xiàng)式的系數(shù)是-5.答案:-56.已知-2xmyn+1的次數(shù)為2,求3m+3n-5的值.【解析】因?yàn)?2xmyn+1的次數(shù)為2,所以m+n+1=2.所以m+n=1(向所求方向進(jìn)行轉(zhuǎn)化).所以3m+3n=3,所以3m+3n-5=3-5=-2.【變式訓(xùn)練】如果(m+1)2x2yn+1是關(guān)于x,y的六次單項(xiàng)式,求

6、m,n的值.【解析】因?yàn)?m+1)2x2yn+1是關(guān)于x,y的六次單項(xiàng)式,所以2+n+1=6,而m+10,解得m-1,n=3.多項(xiàng)式、整式的概念1.多項(xiàng)式-15x2y+22A.1515C.15【解析】選D.原式的第一項(xiàng)為-15x22.多項(xiàng)式5x2-2xy-3的常數(shù)項(xiàng)為()A.沒有B.3【解析】選D.不含字母的項(xiàng)叫常數(shù)項(xiàng).3.式子x2+5,-1,-3x+2,5x,x2+1個個個個【解析】選+5,-1,-3x+2,5x都是整式,共有5個.【知識歸納】單項(xiàng)式、多項(xiàng)式、整式的關(guān)系1.多項(xiàng)式是由單項(xiàng)式組成的,多項(xiàng)式的項(xiàng)是單項(xiàng)式,多項(xiàng)式的次數(shù)就是多項(xiàng)式中次數(shù)最高的單項(xiàng)式的次數(shù),單項(xiàng)式和多項(xiàng)式的區(qū)別在于是否含有加減運(yùn)算.2.單項(xiàng)式與多項(xiàng)式統(tǒng)稱為整式,一個式子不是整式,它一定不是單項(xiàng)式或多項(xiàng)式;反之一個式子既不是單項(xiàng)式又不是多項(xiàng)式,那么它一定不是整式.4.把下列各式填在相應(yīng)的大括號里:x-7,13x,4ab,23a,5-3x,y,st,x+13,x7+y7,x2+單項(xiàng)式集合;多項(xiàng)式集合;整式集合.【解析】單項(xiàng)式集合13多項(xiàng)式集合x-7,x+整式集合13x,4ab,y,8a3x,-1,x-7,x+13,x7+y7,x25.下列各式:ab,-6,1x,m+n3,5x+3,-2x7,m2-2m+1,-p3q,【解析】單項(xiàng)式有:ab,-6,-2x7,-p多項(xiàng)式有:m+n3