《中考课件初中数学总复习资料》第3课时　分式.docx

第3课时分式知能优化训练中考回顾1.(2019天津中考)计算2aa+1+2a+1的结果是()A.2B.2a+2C.1D.4aa+1答案A2.(2018北京中考)如果a-b=23,那么代数式a2+b22a-b·aa-b的值为()A.3B.23C.33D.43答案A3.(2018山东滨州中考)若分式x2-9x-3的值为0,则x的值为. 答案-34.(2019四川泸州中考)化简:m+2+1m·mm+1.解原式=m2+2m+1m·mm+1=(m+1)2m·mm+1=m+1.5.(2019湖北黄石中考)先化简,再求值:3x+2+x-2÷x2-2x+1x+2,其中|x|=2.解原式=x2-1x+2÷(x-1)2x+2=(x+1)(x-1)x+2·x+2(x-1)2=x+1x-1.|x|=2,x=±2.由分式有意义可知,x=2,原式=3.模拟预测1.使分式x-2(x-1)(x-2)有意义,x应满足的条件是()A.x1B.x2C.x1或x2D.x1且x2答案D2.(2019天津二模)化简m2m-4+164-m的结果是()A.m-4B.m+4C.m+4m-4D.m-4m+4答案B3.化简a+3a-4a-31-1a-2的结果等于()A.a-2B.a+2C.a-2a-3D.a-3a-2答案B4.若ab=2,则a2-ab+b2a2+b2的值等于()A.45B.1C.35D.2答案C5.若代数式2x-1-1的值为零,则x=. 答案36.若x+y=1,且x0,则x+2xy+y2x÷x+yx的值为. 答案17.化简并求值:1x-y+1x+y÷2x-yx2-y2,其中x,y满足|x-2|+(2x-y-3)2=0.解原式=2x(x-y)(x+y)·(x-y)(x+y)2x-y=2x2x-y.|x-2|+(2x-y-3)2=0,|x-2|=0,(2x-y-3)2=0.x=2,y=1.原式=2×22×2-1=43.8.先化简再求值:x2-2xx2-1÷x-1-2x-1x+1,其中x是不等式组x+3>0,xx-23+2的整数解.解原式=x(x-2)(x+1)(x-1)÷x2-1-2x+1x+1=x(x-2)(x+1)(x-1)·x+1x(x-2)=1x-1.解不等式组,得-3<x2,则整数解为-2,-1,0,1,2.x2-10,x-20,x0,x±1,x2,x0.x=-2.原式=1-2-1=-13.