（山西专版）中考数学复习第一单元数与式课时训练04分式.docx

课时训练(四)分式(限时:20分钟)|夯实基础|1.2019衡阳如果分式1x+1在实数范围内有意义,那么x的取值范围是()A.x-1B.x-1C.全体实数D.x=-12.2018内江已知1a-1b=13,则abb-a的值是()A.13B.-13C.3D.-33.2019聊城如果分式|x|-1x+1的值为0,那么x的值为()A.-1B.1C.-1或1D.1或04.2019太原模拟计算2aa2-4-1a-2的结果为()A.1a-2B.1a+2C.a-2D.a+25.2019眉山化简a-b2aa-ba的结果是()A.a-bB.a+bC.1a-bD.1a+b6.2019临沂计算a2a-1-a-1的正确结果是()A.-1a-1B.1a-1C.-2a-1a-1D.2a-1a-17.2019衡阳计算:xx-1+11-x=.8.2018武汉计算mm2-1-11-m2的结果是.9.2018攀枝花如果a+b=2,那么代数式a-b2aa-ba的值是.10.2019太原模拟按照一定规律排列的一列数依次为1,65,1210,2017,3026,4237,按照此规律排下去,第n个数是.11.2019杭州化简:4xx2-4-2x-2-1.圆圆的解答如下:4xx2-4-2x-2-1=4x-2(x+2)-(x2-4)=-x2+2x.圆圆的解答正确吗?如果不正确,写出正确的解答.12.2019太原模拟先化简,再求值:1x+1-x+2x2-1(x+1)(x+2)x2-2x+1,其中x=-12.13.2019遂宁先化简,再求值:a2-2ab+b2a2-b2a2-aba-2a+b,其中a,b满足(a-2)2+b+1=0.|拓展提升|14.2019滨州观察下列一组数:a1=13,a2=35,a3=69,a4=1017,a5=1533,它们是按一定规律排列的,请利用其中规律,写出第n个数an=.(用含n的式子表示)【参考答案】1.A2.C3.B4.B5.B6.B7.18.1m-1解析原式=mm2-1+1m2-1=m+1(m+1)(m-1)=1m-1.9.2解析a-b2aa-ba=a2-b2aaa-b=(a+b)(a-b)aaa-b=a+b=2.10.n2+nn2+111.解:圆圆的解答错误.正确解法:4xx2-4-2x-2-1=4x(x-2)(x+2)-2(x+2)(x-2)(x+2)-(x-2)(x+2)(x-2)(x+2)=4x-2x-4-x2+4(x-2)(x+2)=2x-x2(x-2)(x+2)=-xx+2.12.解:原式=1x+1-x+2(x+1)(x-1)(x-1)2(x+1)(x+2)=1x+1-x-1(x+1)2=x+1(x+1)2-x-1(x+1)2=2(x+1)2.当x=-12时,原式=2-12+12=8.13.解:原式=(a-b)2(a+b)(a-b)a(a-b)a-2a+b=a-ba+b1a-b-2a+b=-1a+b.(a-2)2+b+1=0,a=2,b=-1,原式=-1.14.n(n+1)2(2n+1)解析这组分数的分子分别为1,3=2+1,6=3+2+1,10=4+3+2+1,15=5+4+3+2+1,则第n个数的分子为n(n+1)2;分母分别为3=2+1,5=22+1,9=23