第3课时 分式模拟预测1.若代数式x+1(x-3)2有意义,则实数x的取值范围是( ) A.x≥-1B.x≥-1,且x≠3C.x>-1D.x>-1,且x≠32.下列等式中,不成立的是( )A.x2-y2x-y=x-yB.x2-2xy+y2x-y=x-yC.xyx2-xy=yx-yD.yx-xy=y2-x2xy3.如果ab=2,则a2-ab+b2a2+b2的值等于( )A.45B.1C.35D.24.若代数式2x-1-1的值为零,则x= . 5.若x+y=1,且x≠0,则x+2xy+y2x÷x+yx的值为 . 6.化简并求值:1x-y+1x+y÷2x-yx2-y2,其中x,y满足|x-2|+(2x-y-3)2=0.7.已知1a+1b=5(a≠b),求ab(a-b)-ba(a-b)的值.答案2\n1.B 2.A 3.C 4.3 5.16.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=43.7.解:∵1a+1b=5(a≠b),∴a+bab=5.原式=a2ab(a-b)-b2ab(a-b)=(a+b)(a-b)ab(a-b)=a+bab=5.2
