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一、选择题1.(市朝阳区初二期末)下列计算正确的是A.235aaaB.325()aaC.22(3)6aaD.2841aaa答案:A2.(市东城区初二期末)下列运算正确的是A.532bbbB.527()bbC.248bbbD.2-22aabaab()解:A3.(市海
淀区八年级期末)下列计算正确的是A.325aaaB.325aaaC.236(2)6aaD.623aaa答案:B4.(市师达中学八年级第一学期第二次月考)5.(西城区二模)下列运算中,正确的是A.22456xxxB.326xxxC.236()xxD.33
()xyxy答案:C6.(东城区二模)6.如果23510aa,那么代数式5323+232aaaa的值是A.6B.2C.-2D.-6答案A7.(朝阳区二模)6.已知aa252,代数式)1(2)2(2aa的值为(A)11
(B)1(C)1(D)11答案:D8.(石景山区初三毕业考试)下列各式计算正确的是A.23525aaaB.23aaaC.623aaaD.235()aa答案:B9.(市大兴区检测)下列运算正确的是A
.236(2)6aaB.325aaaC.224246aaaD.222(2)4abab答案B10.(延庆区初一第一学期期末)4.下列计算中,正确的是A.22254abababB.ababC.33624aaD.235235bbb答案:A11.(平谷区初一第一学期
期末)下列运算正确的是A.4x-x=3xB.6y2-y2=5C.b4+b3=b7D.325abab+=答案A12.(朝阳区七年级第一学期期末)下列计算正确的是A.2233xxB.22232aaaC.3(
1)31aaD.2(1)22xx答案:D13.(丰台区初一第一学期期末)下列运算正确的是A.33323aaaB.34mmC.022abbaD.2532xxx答案:A14.(朝阳区七年级第一学期期末)李
老师用长为6a的铁丝做了一个长方形教具,其中一边长为b-a,则另一边的长为A.7abB.2abC.4abD.82ab答案:C15.(东城区初一第一学期期末)下列运算正确的是A.43mmB.33323aaaC.220ababD.2
yxxyxy答案:B16.(海淀区七年级第一学期期末)下列结论正确的是()A.23ab和2ba是同类项B.π2不是单项式C.a比a大D.2是方程214x的解答案:A17.(怀柔区初一第一学期期末)如图,正方形的边长为a,圆的直径是d,用字
母表示图中阴影部分的面积为A.22adB.22adC.2212adD.22()2da答案D18.(怀柔区初一第一学期期末)如果23(2)0ab,那么代数式2017()ab的值为A.5B
.-5C.1D.-1答案D19.(延庆区初一第一学期期末)元旦,是公历新一年的第一天.“元旦”一词最早出现于《晋书》:“颛帝以孟夏正月为元,其实正朔元旦之春”.中国古代曾以腊月、十月等的月首为元旦.1949年中华人民共和国以公历1月1日为元旦,因此元旦在中国也被称为“阳历年”.为庆祝元旦,人
民商场举行促销活动,促销的方法是“消费超过100元时,所购买的商品按原价打8折后,再减少20元”.若某商品的原价为x元(x>100),则购买该商品实际付款的金额(单位:元)是A.80%x-20B.80%(x-20)C.20%x-20D
.20%(x-20)答案:A二、填空题20.(房山区二模)10.若代数式26xxb可化为2()5xa,则ab的值为.答案:121.(顺义区初一第一学期期末)13.多项式32232421xyxyxyy是次项式.答案:四次五项式22.(顺义区初一第一学期期末)16.如果23xy
,那么代数式142xy的值为.答案:-523.(顺义区初一第一学期期末)18.如果21(1)0xy,那么代数式20172018xy的值是.答案:-224.(石景山区初一第一学期期末)若710xy与415mxy是同类项,则m的值为.答
案:225.(怀柔区初一第一学期期末)单项式343xy的系数是,次数是.答案:43,26.(怀柔区初一第一学期期末)如果2a-b=-2,ab=-1,那么代数式3ab-4a+2b-5的值是_________.答案:-427.(海淀区七年级第一学期期末)小何买了4
本笔记本,10支圆珠笔,设笔记本的单价为a元,圆珠笔的单价为b元则小何共花费元.(用含a,b的代数式表示)答案:410ab;28.(西城区九年级统一测试)化简:()()42(1)aaaa__________.答案:8a.29.(昌平区初一第一学期期末)234xy的系数是,次数是
.答案:-4,530.(昌平区初一第一学期期末)写出32mn-的一个同类项.答案:答案不唯一,如m3n等.31.(东城区初一第一学期期末)单项式﹣xy2的系数是;次数是_________.答案:1-32,32.(东城区初一第一学期期末)已
知代数式2x﹣y的值是12,则代数式﹣6x+3y﹣1的值是.答案:33.(东城区初一第一学期期末)13.写出一个与32xy是同类项的单项式为______.答案:3xy(答案不唯一)34.(房山区一模)如图,正方形ABCD,根
据图形,写出一个正DCBAabababba确的等式:__________.答案2222abaabb35.(市朝阳区综合练习(一))赋予式子“ab”一个实际意义:.答案答案不惟一,如:边长分别为a,b的矩形面积36.(平谷区中
考统一练习)计算:23222333mn个个=.答案23nm37.(平谷区中考统一练习)已知:24aa,则代数式2122aaaa的值是.答案8;38.(东城区初一第一学期期末)14.如图:(图中长度单位:m),阴影部分的面积是______2m答案:2+
420xx39.(东城区初一第一学期期末)19.按下列图示的程序计算,若开始输入的值为x=﹣6,则最后输出的结果是.答案:12040.(丰台区初一第一学期期末)写出一个系数为32且次数为3的单项式.答案:答案不唯一
,如332a41.(门头沟区七年级第一学期期末)两个单项式满足下列条件:①互为同类项;②次数都是3.任意写出两个满足上述条件的单项式,将这两个单项式合并同类项得_______________.答案:略42.(平谷区初一第一学期期末)已知622xy和-313mnxy是同类项,则m-n的值
是答案:043.(西城区七年级第一学期期末)已知222xx,则多项式2243xx的值为.答案:144.(西城区七年级第一学期期末)16.右图是一所住宅的建筑平面图(图中长度单位:m),这所住宅的建筑
面积为m..答案:2218xx45.(延庆区初一第一学期期末)13.写出-21x2y3的一个同类项.答案:ax2y3三、解答题46.(交大附中初一第一学期期末)先化简,再求值:22113122()()223233xxyxyxy,其中,47.(朝阳区七年级第一学期期末)21.已
知2250xy,求223(2)(6)4xxyxxyy的值.解:223(2)(6)4xxyxxyy223664xxyxxyy224xy.因为2250xy,所以225xy.所以原式=10.48.(昌平区初一第一学期期末)24.化简求
值:22(2)33(31)(93)xxxx,其中13x.解:原式=-6x+9x2-3-9x2+x-3„„„„„„„„3分=-5x-6.„„„„„„„„„„4分当13x时,原式=15()63„„„„„„„„„„5分=
133.„„„„„„„„„„6分49.(东城区初一第一学期期末)先化简,再求值:(5a2+2a﹣1)﹣4(3﹣8a+2a2),其中a=﹣1.解:原式=5a2+2a﹣1﹣12+32a﹣8a2=﹣3a2+34a﹣13.………3分当a=﹣1时,原式=﹣3﹣34﹣13=﹣50.………4分
50.(丰台区初一第一学期期末)先化简,再求值:xyyxxyxyyx2223275,其中1x,32y.解:原式=xyyxxyxyyx224675=yxyx2245=yx29.……3分当1x,32y时,原式=32192=–
6.……4分51.(海淀区七年级第一学期期末)已知37=3ab,求代数式2(21)5(4)3ababb的值.答案.解:2(21)5(4)3ababb=4225203ababb=921
2ab…………………………………..2分37=3abQ∴原式=9212ab=3(37)2ab=3(3)2=92=11…………………………………..4分52.(怀柔区初一第一学期期末)21.先化简,再求值:22(22)(21)xxx,其中12
x.解:原式=224421xxx„„„„„„„„„„„„„„1分=2265xx„„„„„„„„„„„„„„„„„„„„„3分当x=12时,原式=2112()6()522135232„„„„„„„„
„„4分53.(门头沟区七年级第一学期期末)23.先化简,再求值:已知210a,求225+212aaaa的值.答案解:225212aaaa2252122aaaa„„„„„„„„„„„„„„„„„„„„„„„2分231a„„„„„„„„„„„„
„„„„„„„„„„„„„„„„3分又∵210a∴21a„„„„„„„„„„„„„„„„„„„„„„„„„„„„„„4分∴原式2313112a„„„„„„„„„„„„„„„„„„„„5分54.(平谷
区初一第一学期期末)22.化简)()(223212aaaa答案解:=2a2-a-1+6-2a+2a2„„„„„„„„„„„„„„„„„„„„„3=4a2-3a+5„„„„„„„„„„„„„„„„„„„„„„555.(平谷区初一第一学期期末)23.先化简,
再求值:若2x,1y,求)332()1(22222xyyxxyyx的值.答案)332()1(22222xyyxxyyx3322222222xyyxxyyx„„„„„„„„„„„„„„„212xy„„„„„„„„„„„„„„„„„„„„4当2
x,1y时,原式=3„„„„„„„„„„„„„„„„„„„„„„„„„„556.(石景山区初一第一学期期末)23.先化简,再求值:22173)6()3xxyxxy(,其中13,3xy.答案.解:原式222736xxyxxy„„„„„„„„„„„„2分2xxy.„„„„
„„„„„„„„„3分当13,3xy时,原式21(3)(3)310.„„„„„„„„„„„„„5分57.(顺义区初一第一学期期末)27.王老师给同学们出了一道化简的题目:222(2)3(2)xyxxyx,小亮同学的做法如下:222222(2)3(2
)432xyxxyxxyxxyxxyx.请你指出小亮的做法正确吗?如果不正确,请指出错在哪?并将正确的化简过程写下来.答案:去括号时应用分配率出错.„„„„„„„„„„„„„„„„„„„2分正确化简结果如下:原式224236xyxxy
x„„„„„„„„„„„„„„„„„„4分28xyx„„„„„„„„„„„„„„„„„„„„„„„„5分58.西城区七年级第一学期期末).先化简,再求值:2223()2()3xxyxyxy,其中1x,3
y.答案:解:2223()2()xxyxyxy=22233223xxyxyxy......................................................................
.......2分=222xy.............................................................................................................3分当1x,3y时,原式=22(1)23
.............................................................................................4分=19.5分
59.(西城区七年级第一学期期末附加题)输液时间与输液速率问题静脉输液是用来给病人注射液体和药品的.在医院里,静脉输液是护士护理中最重要的一项工作,护士需要依据输液速率D,即每分钟输入多少滴液体,来计算输完点滴注射液的时间
t(单位:分钟).他们使用的公式是:dVtD,其中,V是点滴注射液的容积,以毫升(ml)为单位,d是点滴系数,即每毫升(ml)液体的滴数.(1)一瓶点滴注射液的容积为360毫升,点滴系数是每毫升25滴,如果护士给病人注射的输液速率为每分钟50滴,那么输完这瓶点滴注射液需要多
少分钟?(2)如果遇到的病人年龄比较大时,护士会把输液速率缩小为原来的12,准确地描述,在V和d保持不变的条件下,输完这瓶点滴注射液的时间将会发生怎样的变化?答案:(1)由D=50,d=25,360V,dVtD
,∴2536050t............................................................................3分∴t=180.........
.....................................................................4分答:输完点滴注射液的时间是180分钟.(2)设输的速率为D1滴/分,点滴注射的时间为t1分钟,则11dVtD.......................
....................................................................5分输液速率缩小为112D2,点滴注射的时间延长到t2分钟,则21112212d
VdVttDD,....................................................................6分答:在d和V保持不变的条件下,D将缩小到原来的12时,点输完滴注射的时间延长为原来的2倍.
.....................................................................................7分60.(延庆区初一第一学期期末)先化简,再求值:222(22)(21)xxxx,其中12x.答案18.
解:原式=2224421xxxx……………………3分=263xx………………………………………4分当12x时,原式=211()6()3221334234…………………5分61.(房山区二模)已知2212x
x.求代数式2(1)(4)(2)(2)xxxxx的值.答案.原式=2222144xxxxx=2363xx.„„„„„„„„„„„„„„„„„„„„„„„„„„3′∵2212xx∴原式=2363xx23(21)xx
6.„„„„„„„„„„„„„„„4′62.(市朝阳区初二期末)已知0ab,求代数式(4)(2)(2)aababab的值.解:(4)(2)(2)aababab2224(4)aabab„„„„
„„„„„„„„„„„„„„„2分244abb.„„„„„„„„„„„„„„„„„„„„„„„„„3分∵0ab,∴原式4()0bab.„„„„„„„„„„„„„„„„„„„„„5分63.(市东城区初二期末))已知2+2xx
,求22311xxxxx的值【解析】