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  • 当前位置:文档库 > (精)2018-2019第一学期苏科版七年级数学期中试题(有答案)

    (精)2018-2019第一学期苏科版七年级数学期中试题(有答案)

    (第8题)

    b

    a

    2018-2019学年第一学期期中试卷

    七年级数学 2018.11

    考试时间:100分钟 满分分值:110分

    一、选择题(每题3分,共30分)

    1.-6的相反数是 ( ) A .6 B .-6 C .

    61 D .6

    1- 2.在有理数-(+2.01)、20、-432、??? ?

    ?

    --3112、-|-5|中,负数有 ( )

    A .2 个

    B .3 个

    C .4 个

    D .5个

    3.下列两个单项式中,是同类项的一组是

    ( )

    A .3与5

    1

    -

    B .2m 与2n

    C .3xy 2与(3xy )2

    D .4x 2y 与4y 2x

    4.下列说法中正确的是 ( ) A .平方是本身的数是1 B .任何有理数的绝对值都是正数 C .若两个数互为相反数,则它们的绝对值相等 D .多项式2x 2+xy +3是四次三项式 5.在代数式:π

    3233032,,,,,ab a y x ab -- 中,单项式有 ( )

    A .6个

    B .5个

    C .4个

    D .3个

    6.下列运算中,正确的是 ( )

    A .-(x -6)=-x -6

    B .-a +b =-(a +b )

    C .5(6-x )=30-x

    D .3(x -8)=3x -24

    7.用代数式表示“m 的5倍与n 的差的平方”,正确的是 ( )

    A .(5m -n )2

    B .5(m -n )2

    C .5m -n 2

    D .(m -5n )2

    8.有理数a 、b 在数轴上的位置如图所示,则化简a b a -+的结果为 ( ) A .b a --2 B .a C .-a D .b

    9.已知多项式x 2-kxy -3(x 2

    -12xy +y)不含xy 项,则k 的值为 ( ) A .-36 B .36 C .0 D .12

    10.如果一个数列{a n }满足31=a ,n a a n n 31+=+(n 为自然数),那么20a 是 ( ) A .603 B .600 C .570 D .573

    二、填空题(每空2分,共20分) 11.-4的绝对值是 ,5

    2

    -

    的倒数是 . 12.据统计,2018年国庆七天假期,无锡鼋头渚公园的接待游客量达178000人次,178000用科学记数法表示为 .

    学校: 班级: 姓名: 考试号:

    订线内

    13.数轴上与表示-5的点距离2个长度单位的点所表示的数是 .

    14.代数式5

    22

    3bc a -是______次单项式,系数为________.

    15.有一列数:-22、(-3)2、-|-5|、0,请用“<”连接排序:_________________. 16.若9,5x y ==,且0<xy ,那么x -y =__________. 17.若x 2+3x -3的值为8,则3x 2+9x +4的值为 . 18.按图示的程序计算,若开始输入的x

    (精)2018-2019第一学期苏科版七年级数学期中试题(有答案)

    最后输出的结果为67,则x 的值是 .三、解答题(本题共7题,共60分) 19.(本题16分)计算:

    (1)-5-(-4)+7-8 (2)()5

    135213?-÷

    (3)()94312

    4

    -

    ?--- (4))5

    2

    3(12523)7()523()5(-?-?-+-?-

    20.(本题8分)化简:

    (1)3y 2-9y +5-y 2+4y -5y 2 (2)5(3a 2b -2ab 2)-3(4ab 2+a 2b )

    21.(本题6分)“囧”像一个人脸郁闷的神情.如图,边长为a 的正方形纸片,剪去两个一样的小直角三角形(阴影部分)和一个长方形(阴影部分)得到一个“囧”字图案,设剪去的两个小直角三角形的两直角边长分别为x 、y ,剪去的小长方形长和宽也分别为x ,y . (1)用含a 、x 、y 的式子表示“囧”的面积; (2)当a =12,x =7,y =4时,求该图形面积的值.

    (精)2018-2019第一学期苏科版七年级数学期中试题(有答案)

    22.(本题6分)某食品厂从生产的袋装食品中抽出样品20超过或不足的部分分别用正、负数来表示,记录如下:

    (第18题)

    (精)2018-2019第一学期苏科版七年级数学期中试题(有答案)

    ....总质量是多少? 23.(本题8分)某工厂以90元/箱的价格购进50箱原材料,准备由甲、乙两车间全部用于生产 A 产品.甲车间用每箱原材料可生产出A 产品15千克,需耗水6吨;乙车间通过节能改造,用每箱原材料可生产出的A 产品比甲车间少3千克,但耗水量是甲车间的一半.已知A 产品售价为40元/千克,水价为5元/吨,若分配给甲车间x 箱原料用于生产A 产品. (1)试用含x 的代数式填空:

    ①乙车间用__________箱原料生产A 产品; ②两车间共生产A 产品__________千克;

    ③两车间共需支付水费 元(答案化到最简).

    (2)用含x 的代数式表示两车间生产A 产品所获得的利润;并计算当x =30时,利润是多少?如果

    要求这两车间生产A 产品的总耗水量不得超过240吨,计算当x =30时符合要求吗?(注:利润=产品总售价一购买原材料成本一水费)

    24.(本题6分) 设a 1=22-02,a 2=32-12,…,a n =(n +1)2-(n -1)2(n 为大于1的整数) (1)计算a 15的值;

    (2)通过拼图你发现前三个图形的面积之和与第四个正方形的面积之间有什么关系:

    (精)2018-2019第一学期苏科版七年级数学期中试题(有答案)

    (精)2018-2019第一学期苏科版七年级数学期中试题(有答案)

    (精)2018-2019第一学期苏科版七年级数学期中试题(有答案)

    (精)2018-2019第一学期苏科版七年级数学期中试题(有答案)

    __________________________________(用含a 、b 的式子表示);

    ① ② ③

    (3)根据(2)中结论,探究a n =(n +1)2-(n -1)2是否为4的倍数.

    25.(本题10分)已知:c =10,且a ,b 满足(a +26)2+|b +c |=0,请回答问题: (1)请直接写出a ,b ,c 的值:a = ,b = ;

    (2)在数轴上a 、b 、c 所对应的点分别为A 、B 、C ,记A 、B 两点间的距离为AB ,则AB= ,

    b

    a

    a b

    AC= ;

    (3)在(1)(2)的条件下,若点M 从点A 出发,以每秒1个单位长度的速度向右运动,当点M 到达点C 时,点M 停止;当点M 运动到点B 时,点N 从点A 出发,以每秒3个单位长度向右运动,点N 到达点C 后,再立即以同样的速度返回,当点N 到达点A 时,点N 停止.从点M 开始运动时起,至点M 、N 均停止运动为止,设时间为t 秒,请用含t 的代数式表示M ,N 两点间的距离.

    2018-2019学年第一学期期中试卷

    参考答案

    一、选择题

    1. A

    2.B

    3.A

    4.C

    5.C

    6.D

    7.A

    8.D

    9.B 10.D

    二、填空题 11. 4 25-

    12. 5

    1078.1? 13.7-或3- 14. 六 5

    2- 15. ()2

    2

    3025----<<< 16.14或-14 17.37 18. 2,7,22

    四、解答题 19.计算:

    (1)-5-(-4)+7-8 (2)()5135213

    ?-÷ =-5+4+7-8·················(2分) =51

    35127??-······························(2分) =-2····························(4分) =50

    1

    -·········································(4分)

    (4)()943124

    -?--- (4))5

    23(12523)7()523()5(-?-?-+-?-

    =9491?

    --························(2分) =5

    2

    31252375235?+?-?················(1分) =-1-4·······························(3分) =()12755

    2

    3+-?····························(3分)

    =-5···································(4分) =34················································(4分) 20.化简:

    (1)3y 2-9y +5-y 2+4y -5y 2 (2)5(3a 2b -2ab 2)-3(4ab 2+a 2b )

    =-3y 2-5y +5·····················(4分) =15a 2b -10ab 2-12ab 2-3a 2b ·········(2分)

    =12a 2b -22ab 2···························(4分)

    21.(1)a 2

    -xy ×2-xy =a 2

    -2xy ;··························································(3分)

    (2)当a =12,x =7,y =4时,

    原式=122-2×7×4=88 ···········································································(6分)

    22. -4×3+2×5+0×3+1×4-3×2+5×3=11······················································(2分)

    11÷20=0.55(g),所以这批样品的平均质量比标准质量多0.55g····························(4分) (450+0.55)×20=9011(g),所以抽样的总质量是9011g .·········································(6分)

    23.(1) (50-x ) (3x +600) (15x +750)····························································(3分)

    (2) 40(600+3x )-90×50-(750+15x )=105x +18750············································(5分) 当x =30时,原式=21900··········································································(6分) 耗水量为(3x +150)千克,当x =30时,3x +150=240,所以符合要求.······················(8分)

    24.(1)a 15=162-142=256-196=60·······································································(2分)

    (2) (a +b )2=a 2+2ab +b 2 ··············································································(4分)

    (3) a n =(n +1)2-(n -1)2 =(n 2+2n +1)-(n 2-2n +1) =n 2+2n +1-n 2+2n -1=4n

    n a 是4的倍数. ···············································································(6分)

    25.(1)a = -26,b =-10;···············································································(2分) (2) AB=16;AC=36;·····················································································(4分) (3)①当0≤t ≤16时,MN=t ,

    ②当16<t ≤24时,MN=t -3(t -16)=-2t +48, ③当24<t ≤28时,MN=3(t -16)-t =2t -48,

    ④当28<t ≤30时,MN=36×2-t -3(t -16)=-4t +120, ⑤当30<t ≤36时,MN=4(t -30)=4t -120,

    ⑥当36<t ≤40时,MN=3(t -16)-36=3t -84.··················································(10分)